The hosts were well on their way to victory at the start of play on day four, with three Ashwin wickets helping them drop the tourists to 158-4 on Saturday, chasing a daunting target of 515.
Bangladesh captain Najmul Hossain Shanto kept India waiting for their fifth wicket on Sunday, his resistance defining a wicketless first hour of play.
However, after drinks, Chennai local Ashwin and Chennai Super Kings star Ravindra Jadeja combined to brilliant effect to rip through the visitors.
Ashwin made the breakthrough by having Shakib Al Hasan caught for 25 from just his fourth delivery of the day, then Jadeja's full ball was helped straight to Rohit Sharma at first slip by Litton Das (1).
Ashwin brought up his five-for soon afterwards by dismissing Mehidy Hasan Miraz (8), then Shanto's courageous knock of 82 was finally brought to an end by Jadeja, the Bangladesh skipper's top edge being well held by Jasprit Bumrah.
Jadeja finished 58-3 by bowling Hasan Mahmud (7) for the final wicket, but not before Ashwin had brought up his sixth dismissal, having Taskin Ahmed caught for five runs.
India will now look to clinch the two-match series when the second Test gets underway in Kanpur on Friday.
Data Debrief: Ashwin closing on Botham
Ashwin's first-innings knock of 113 helped India build a commanding lead before Bangladesh took up the bat for the second time on Friday, and he was equally brilliant with the ball.
Having dismissed three before stumps on Friday, he did likewise in an enjoyable second session on Saturday, bringing up his 37th five-for in red-ball cricket.
It is the fourth time he has hit a hundred and scalped five wickets in a single Test, and he has also done so in successive Tests in Chennai. Only England great Ian Botham (five times) has ever achieved both feats in the same Test more often.
Saturday's match went right to the wire with South Africa requiring 16 runs from the final over, but Hardik Pandya clinched a hat-trick with the late dismissals of David Miller and Kagiso Rabada as the Proteas lost their nerve.
Virat Kohli had earlier smashed 76 runs off 59 balls, comfortably his best score of the tournament, to help India set a daunting target of 177 – the highest ever in a men's T20 World Cup final.
Kohli's innings came to an end in the penultimate over as he swung Rabada's delivery straight to Marco Jansen at long-on, after partner Axar Patel (47) was run out by Quinton de Kock.
That knock proved to be the title clincher, though, as the India bowlers provided able support to their batsmen.
South Africa were reduced to 12-2 within the first three overs as Jasprit Bumrah sent wickets flying with a brilliant outswinger to beat Reeza Hendricks (4) and Arsheep Singh had Aiden Markram (4) caught behind by Rishabh Pant.
If India thought they would be able to defend their total in comfort, however, they were mistaken.
Heinrich Klaasen slammed 52 off 27 balls with support from De Kock (39) and Tristan Stubbs (31), to take them close.
Thirty runs from as many deliveries was the target at one point, but Klaasen nicked Pandya's ball through to Pant in the 17th over and Bumrah followed up by dismissing Jansen for two.
The tail was unable to provide the heroics for South Africa, desperate final-over swings from Miller (21) and Rabada (4) going unrewarded as Pandya finished with an efficient 3-20.
Kohli picks his moment
Kohli has not been on top form throughout this tournament, 37 versus Bangladesh his best score until this point with five of his innings bringing single-digit tallies.
He stepped up when it mattered most, though, becoming just the third player to make a half-century in multiple T20 World Cup finals, having made 77 in India's 2014 loss to Sri Lanka (also Marlon Samuels and Kumar Sangakkara).
After being presented with the Man-of-the-Match award, Kohli suggested he will not play at the next edition of the tournament in 2026. If his T20I career is over, he certainly went out on a high.
Klaasen's historic knock in vain
South Africa ran India close despite being tasked with chasing the best total ever recorded in a T20 World Cup final, and that was mostly due to Klaasen's efforts.
He made his half-century in 23 balls, the fastest 50 in a T20 World Cup final. He obliterated the previous record, Mitchell Marsh's 31-ball half-century for Australia in 2021.
Long wait over for India
Most observers would agree India are fitting champions, having marked themselves out as the best team at the tournament during the last few weeks.
It is their first T20 World Cup crown since they won the inaugural edition in 2007, and they have joined England and West Indies as the only teams to triumph more than once (two titles each).
The left-arm spinner accounted for Tom Latham, who was just five runs short of a century, before making light work of the lower order to finish with figures of 5-62.
It was the fifth five-four Axar has recorded in his previous seven innings in Test cricket and it seemed to inspire the rest of India's attack as they left New Zealand all out on 296.
Latham and Will Young had put New Zealand in a commanding position of 129-0 at the close of day two, and their partnership of 151 steered the Black Caps to 213-2 despite the best efforts of Axar and Ravichandran Ashwin (3-82).
However, the match changed course in the afternoon session. Umesh Yadav trapped Kane Williamson lbw after the captain managed just 18 off 64 deliveries, and Axar took the wickets of Ross Taylor (11) and Henry Nicholls (2) while only giving up 14 runs in an 11-over spell.
Tom Blundell and Tim Southee were then skittled by Axar, who capped his performance by catching Kyle Jamieson just as he was building up steam on 23.
There was time for India to put some runs on the board before the light faded, although the excitable crowd in Kanpur was stunned into eerie silence when Jamieson bowled Shubman Gill for his 50th Test wicket with the first ball of the second over.
India will resume on day four on 14-1 with a lead of 63 runs.
Axar hogging the limelight
New Zealand looked to have the match under their control at 196-1 until Axar intervened. It was his fifth five-wicket haul of 2021; the last player to record as many in the year of his Test debut was Australia's Rodney Hogg back in 1978.
"Taking five wickets in seven innings is something the other team-mates have been teasing me about. It's like a dream within a dream start," he said.
Jamieson keeps up New Zealand spirits
After failing to make the most of Latham and Young's impressive opening stand, New Zealand heads were down as India began their second innings.
However, Jamieson's terrific ball to Gill might just have halted the hosts' momentum. It also made the 26-year-old the fastest man to reach 50 Test wickets for New Zealand, his half-century coming in just nine matches, with previous record-holder Shane Bond doing so in 12.
A potential switch had previously been mooted, with reports that the outfield at Dharamsala's Himachal Pradesh Cricket Association Stadium was not ready after being re-laid.
The BCCI confirmed the move on Monday for the third Test due to commence on March 1.
"Owing to harsh winter conditions in the region, the outfield lacks sufficient grass density and will need some time to develop fully," the BCCI statement said.
The schedule remains the same, with the Test starting on March 1, but to be played at Holkar Stadium in Indore in Madhya Pradesh, roughly 600 kilometres north-east of Mumbai.
India lead the series 1-0 after a comprehensive first Test triumph in Nagpur, winning by an innings and 132 runs inside three days.
The penultimate encounter in the Border-Gavaskar Trophy contest is scheduled to take place between March 1 and March 5 at Himachal Pradesh Cricket Association Stadium.
But the fixture looks set to be relocated, with Bengaluru or Visakhapatnam potentially in line to stage the game.
The Times of India quoted an unnamed source from the Board of Control for Cricket in India as saying the outfield in Dharamsala was not ready after being relaid.
Australia's last visit for a Test to Dharamsala came in March 2017, when India clinched a 2-1 series victory with an eight-wicket triumph over the tourists.
The hosts are already one up in the current series, after racing to an innings-and-132-run win inside three days in Nagpur.
Pat Cummins' touring side will hope to level matters when the second Test rolls around, with the game set to start in Delhi on Friday.
India, meanwhile, have announced the departure of Jaydev Unadkat from their squad ahead of the second Test, allowing him to play in Thursday's Ranji Trophy final for Saurashtra.
India, who claimed a 3-1 Test series victory earlier this month, drew level with their visitors in the 20-over format with victory in Sunday's second match.
But the final three encounters will go ahead without fans in the stadiums.
Ahmedabad's Narendra Modi Stadium is hosting all five matches and welcomed supporters in large numbers for the first two limited-overs meetings.
However, India has seen another rise in positive COVID-19 tests, with over 24,000 new cases reported on Monday.
The England and Wales Cricket Board (ECB) subsequently confirmed it had been told of the change in plans, although it added the decision would have no impact on the England team.
"We have just received confirmation that the remaining T20I matches will take place without spectators," the ECB said in a statement released to Stats Perform News.
"We have also seen the statement by the vice-president of the Gujarat Cricket Association confirming the fact.
"Aside from meaning there will be considerably less noise in the stadium, it doesn't materially affect us as we remain in our bubble and, even when crowds were in attendance, we never came into contact with any of them, and the ball was sanitised whenever it was hit into the stands."
The two neighbouring nations, who share a complex history, have not played one another in cricket's longest format since 2007.
Pakistan have only recently seen the resumption of home matches for the first time in 10 years.
But the ECB is said to be working on a plan to have India play Pakistan on neutral in England. ESPNcricinfo reports Pakistan are unlikely to take up the offer as the PCB concentrates on hosting matches itself.
It is an idea that appeals to Moeen – an England international of Pakistani descent.
"That would be awesome, brilliant," he said. "It's a shame that they don't play each other unless it's a World Cup or an ICC event because they're two great teams and two massive playing nations.
"With the viewing figures involved, it would be one of the biggest games, and it’s not been done for a very long time.
"It would be great because Pakistan have a really good bowling attack, and India have a great Test side. It would be really good."
Rohit Sharma's side had already secured progression from Group A to the Super 8s, while co-hosts Canada could not escape the pool after two losses and a sole victory.
The match on Saturday was called off without a ball being bowled due to the persistent downpour at Lauderhill.
India, Australia, and Afghanistan have all qualified to feature in Group 1 of the Super 8s, which starts on Wednesday.
The 35-year-old starred in India's 2007 ICC World Twenty20 final against Pakistan, taking 3-16 to help steer his country to victory in South Africa.
All-rounder Irfan first shot to stardom back in 2003 when he claimed figures of 9-16 for India Under-19s against Bangladesh, earning him a spot in the senior squad for a tour of Australia.
He confirmed his decision to call it quits in an interview on Star Sports on Saturday.
"I am announcing retirement from all forms of cricket," said Irfan. "I have been fortunate to share the dressing room with greats of the game like [Sourav] Ganguly, [Rahul] Dravid and [VVS] Laxman. I am calling time on my career.
"I would like to thank my family for providing much-needed support. I would like to thank my fans. They have always hoped for my comeback. Their support has kept me going."
Irfan, who last played on the international stage in 2012, featured in 29 Tests, 120 ODIs and 24 T20s for his country.
Having clawed back from 2-0 down in the series to set up a winner-takes-all meeting on Sunday, India made a slow start in Bengaluru in a match that was initially reduced to 19 overs because of poor weather.
Lungi Ngidi removed both Ishan Kishan (15) and Ruturaj Gaikwad (10) to leave India 28-2, with Shreyas Iyer and captain Rishabh Pant at the crease.
But the downpour resumed, leading to the abandonment of the match with just 21 balls having being bowled.
Travis Head's 137 propelled Australia to a six-wicket victory in Sunday's final at Narendra Modi Stadium in Ahmedabad.
Head's knock is the second-highest score by an opener in a men's World Cup final.
And Madan Lal, who played for India between 1974 and 1987, believes the tournament hosts had a mental slip at the most inopportune moment.
"It is a little bit of a mental issue, you can say that," he told Stats Perform.
"In a final, if you make mistakes, then you have no chance of winning. You have to make less mistakes [than the opposition] as that is the only way you are going to win.
"You can say [India are having] mental issues because in the last 10 ICC tournaments we've played in the finals [knockout rounds], but we didn't win any. That can be addressed.
“Definitely [this was their best chance] because of the way the team was playing and the way their bowling attack was performing.
"I was thinking that India would go through and win, but at the end of the day, when Australia came into the final, then I said it was a 50-50 game. It's not a game that can be easily won.
"I think it's a bit sad. India had done very well. They won all their ten matches, but in the last one, they couldn’t cross the line."
Virat Kohli starred for India in the World Cup, scoring 765 runs.
He tallied a half-century in the final, having plundered a ton in the semi-final, which took him above India legend Sachin Tendulkar in the all-time rankings for ODI centuries.
"He’s fantastic, a world champion, a superb player," Madan Lal said of Kohli.
"The good thing about him is the way he looks after himself, the way he approaches the game, his attitude.
"Plus, if you see when he's batting, we always know that if he bats for 15 minutes, he will get 100 runs.
"And another good thing about him is that he looks at the scoreboard. He plays according to the situation of the game, like Head did [in the final]."
Ashwin became just the ninth bowler in history and second Indian after Anil Kumble to reach 500 Test wickets on Friday when he dismissed Zak Crawley in the final session of the second day.
However, just a few hours after the close of play, the Board of Cricket for Control in India announced Ashwin had immediately pulled out of the squad and his availability for the last three days is unknown.
“In these challenging times, the Board of Control for Cricket in India (BCCI) and the team fully supports Ashwin,” read a statement from the BCCI secretary Jay Shah.
“The BCCI extends its heartfelt support to the champion cricketer and his family. The health and well-being of the players and their loved ones are of utmost importance.
“The board requests respect for the privacy of Ashwin and his family as they navigate through this challenging time.”
A tweet from BCCI vice-president Rajeev Shukla added: “Wishing speedy recovery of mother of @ashwinravi99. He has to rush and leave Rajkot test to Chennai to be with his mother”
The batsman sustained the setback when he slipped outside the dressing room in Chennai on Tuesday.
He will now be sidelined for the opening pair of fixtures as England head into a four-match series with Virat Kohli's side.
"Following the results of last night's scan, England top-order batsman Zak Crawley has been ruled out of the first two Tests of the India versus England series," read Thursday's statement from the England and Wales Cricket Board.
"Scan results have confirmed that Crawley has jarred his right wrist, which has sprained the joint and led to local inflammation.
"The Kent player sustained the injury during England's practice in Chennai on Tuesday when he slipped on the marble floor leaving the dressing rooms onto the field of play.
"The England medical team will continue to assess his progress over the next few weeks."
Crawley opened in Sri Lanka in the absence of Rory Burns but looked set to move to number three at M. A. Chidambaram Stadium after Jonny Bairstow was rested.
England will now have to rethink the order, although there was positive news over Ollie Pope, who has recovered from a shoulder injury and could make his comeback after being added to the squad.
Pope damaged a muscle in his left thigh while batting for Surrey in a Vitality Blast match against Kent Spitfires last week.
He is a doubt for the first game of the series against Virat Kohli's side at Trent Bridge on August 4.
The England and Wales Cricket Board stated: "England batsman Ollie Pope has been ruled out until England's Test Series against India after suffering a left thigh muscle injury.
"Pope sustained the injury while batting during Surrey’s Vitality Blast match against Kent Spitfires on Friday 2 July.
"The ECB and Surrey fitness teams will work together to deliver Pope’s rehabilitation with a focus for him to be available to return for the first Test against India."
It is another unfortunate setback for Pope, who underwent shoulder surgery after dislocating his shoulder in a Test against Pakistan last August – the second time he had suffered that injury.
Morgan required four stitches in his right hand after the batsman split the webbing between his thumb and index finger in an opening match that was won by India on Tuesday.
England's white-ball captain took part in a fielding drill at the MCA Stadium on Thursday but declared himself unfit to feature in the two remaining contests in Pune.
Jos Buttler will lead the team in the absence of Morgan, while Liam Livingstone is to make his ODI debut in the second match of the series on Friday.
Morgan said: "I had the hand re-dressed before the start of training today [Thursday] but it quickly became apparent that I found myself protecting the injury and getting into the wrong positions to catch the ball.
"There's nowhere to hide on the field in international cricket these days, especially in limited-over formats so it didn't require any great thought to make myself unavailable.
"It was a freak injury and it's extremely frustrating but there's nothing I can do about it. It's now just a case of letting the cut heal. I have every confidence in Jos and the rest of the squad coping without me."
Sam Billings will not feature in the second ODI and the batsman will be checked again ahead of the final encounter on Sunday, having bruised his left collarbone in a 66-run defeat on Tuesday.
Dawid Malan, already in the touring party as cover, has been added to the squad.
Wood suffered a shoulder injury attempting to prevent a boundary during a dramatic 151-run defeat at Lord's.
The paceman was able to return to the field and bowl but may not be available in Leeds next week when England attempt to hit back from a shattering loss at the Home of Cricket.
Head coach Silverwood said of Wood's fitness: "The medics are working on him. We'll find out more in the next couple of days.
"We will make a decision, along with him and our medics, closer to the time. But if he's not right, he's not right. I certainly won't push him into playing if he tells me he's not right. I will look after him."
England are already without Jofra Archer, Olly Stone and Stuart Broad due to injury and Silverwood says they cannot afford to take any chances with Wood.
"What he did for the team, and the effort to bowl at 90mph with a sore shoulder, it just shows how much he cares about the team and how much he cares about playing for England, and how passionate he is," he said.
"It was a superb effort. I'm very proud of him for what he did there. He'll be trying his best to get ready for Leeds, and I will give him every chance to be fit, but at the same time, it is massively important that we look after Woody.
"He is a prized asset. We have found ourselves in the position, when you lose Archer and Stone, we have got one guy left that can bowl that fast."
England crumbled to 120 all out on Monday to go 1-0 down in the five-match series, with Dom Sibley and Rory Burns falling without scoring and Haseeb Hameed only making nine following a first-innings golden duck.
The prospect of Dawid Malan and James Vince being called up was put to Silverwood on Tuesday and he said other options will be discussed.
"I've got to keep my eyes and ears open, and my mind open to all suggestions, and it's certainly something that we'll be talking about this evening in selection, when we all get together," Silverwood said.
"It's not like I'm not in touch with these guys. I've seen them over the various formats and my relationship with these guys is very good. I'm quite close to them so I wouldn't say you can't do it.
"I don't think there is any ideal process out there. We have to make the best of what we've got. It's difficult to bring people in from, say, the Hundred or the Royal London Cup.
"To throw them into Test cricket, we've seen that the pressure is huge in this series. It's being played with a lot of passion, which is great to see, but it is a difficult transition.
"You've got to do what's best for the team, ultimately, and find the best way of progressing England to a place where big first-innings runs – and second-innings runs – come in on a consistent basis."
Uncapped Auckland bowler Kyle Jamieson has earned a maiden call-up for the three-game series, which starts on February 5 in Hamilton, while Scott Kuggeleijn and Hamish Bennett have been selected for the first time since 2017.
The Black Caps are without Trent Boult (broken hand), Lockie Ferguson (calf strain) and Matt Henry (broken thumb), leaving Tim Southee as their only experienced frontline bowler.
"Tim Southee has an important job leading our new-look pace attack, which has a huge opportunity against some of the very best batsmen in the world," said head coach Gary Stead.
"While the bowling line-up has a fresh look, the batting is very settled and we'll likely have the same top eight batsmen from the World Cup finals."
Wicketkeeper-batsman Tom Latham is fit again after recovering from a broken finger.
"It's great to have Tom fit so we can call on his experience behind the stumps and in the middle order," Stead added.
The former India captain announced he has played his last game for his country in a brief Instagram post.
Dhoni's decision came as no surprise given he turned 39 last month and has not played for India since a Cricket World Cup semi-final defeat to New Zealand last year.
The maverick wicketkeeper-batsman became the only skipper to inspire his side to Cricket World Cup, World Twenty20 and Champions Trophy glory, while India also topped the Test rankings during his reign.
With assistance from Opta, we pick out a selection of the staggering numbers Dhoni racked up in a stellar India career.
17,266 - The number of runs Dhoni scored, a tally bettered only by Sri Lanka great Kumar Sangakkara (17,840)
332 - Dhoni captained his country 332 times, more than any other skipper. Ricky Ponting (324) is next on the list.
535 - He played for his country over 500 times, a landmark only eight other men have passed – including the likes of Sachin Tendulkar, Ponting and Sangakkara.
123 - Dhoni is the only wicketkeeper to register over 100 ODI stumpings, finishing with 123.
195- He quit with 195 stumpings across all three formats, which is another record.
444 - The India legend sits third on the list of most ODI dismissals with 444, behind Sangakkara (482) and Adam Gilchrist (472).
50.57 - Dhoni is one of only five men (who have played at least 100 games) to average over 50 with the bat in ODI cricket. Virat Kohli, Michael Bevan, AB de Villiers and Joe Root being the others.
229 - Just five men have hit more ODI sixes than the powerful right-hander, who cleared the ropes 229 times in the 50-over format.
This year's edition of the Twenty20 tournament was originally due to start in March, only to be postponed indefinitely amid the coronavirus pandemic.
With COVID-19 cases continuing to rise in the country, the Board of Control for Cricket in India (BCCI) had already revealed plans to stage the entire competition in the United Arab Emirates later in the year.
Following a video conference between members of the IPL's governing council on Sunday, a statement signed by BCCI secretary Jay Shah announced further details regarding the 53-day event, including venues, updated regulations and key dates.
The final is due to be played on November 10 and there will be 10 double-headers during the round-robin stage, though a full fixture list is yet to be released.
The UAE has staged the IPL previously, co-hosting the 2014 season due to a clash with India's general election.
"The governing council also discussed the comprehensive standard operating procedures (SOPs), which will be finalised and published in due course, including the agencies to execute and deliver a bio-secure environment for safe and successful conduct of IPL 2020 Season," the statement read.
"The governing council also reviewed the player regulations for replacement players for 2020 season."
The IPL governing council plans to hold a meeting with all franchises in the near future, while the proposals must be ratified by the Indian government.
the Women's T20 Challenge will also take place in the UAE, with three teams playing four matches during the same week as the IPL play-offs.
A statement released by the Board of Control for Cricket in India (BCCI) on Saturday outlined the planned resumption of a campaign that was suspended in early May amid the worsening coronavirus crisis within the country.
The 2021 edition of the Twenty20 tournament was halted following positive cases within the IPL bubble, forcing fixtures to be rearranged.
However, the BCCI's media release said the switch in location had been made to avoid clashing with the monsoon season in India, which usually begins in late May or early June and continues through into October.
Last year's tournament was staged entirely in the UAE due to the COVID-19 pandemic, with Mumbai Indians winning a fifth title by beating Delhi Capitals in the final.
As well as announcing a new venue for the IPL, the BCCI revealed they will "seek an extension" from the International Cricket Council over a decision on the T20 World Cup, which India is due to stage in October and November.
"The Board of Control for Cricket in India (BCCI) on Saturday announced to complete the remaining matches of VIVO Indian Premier League 2021 season in the United Arab Emirates (U.A.E) considering the monsoon season in India in the months of September-October this year," the BCCI statement read.
"The decision was taken at a special general meeting (SGM) held virtually, where members unanimously agreed to resume IPL.
"The BCCI SGM further authorised the office bearers to seek an extension of time from the ICC to take an appropriate call on the hosting of ICC T20 World Cup 2021."
The fifth and final Test of India's series in England begins at Old Trafford on September 10.
