Froome is out of contract in December and will part ways with the David Brailsford-helmed outfit – formerly known as Team Sky – because he can no longer be guaranteed sole team leadership.
The 35-year-old triumphed at Le Tour in 2013, 2015, 2016 and 2017, although INEOS' domination of road cycling's premier event continued with Geraint Thomas taking glory in 2018 and Egan Bernal prevailing in Froome's injury absence last year.
A scramble for the services of one of the sport's all-time greats is now set to ensue, although Cycling News reports Froome has agreed a multi-year contract with Israel Start-Up Nation.
"It has been a phenomenal decade with the team, we have achieved so much together and I will always treasure the memories," said Froome, who also won the Vuelta a Espana in 2011 and 2017 before completing the set of cycling's Grand Tours at the 2018 Giro d'Italia.
"I look forward to exciting new challenges as I move into the next phase of my career, but in the meantime my focus is on winning a fifth Tour de France with Team INEOS."
Froome superseded 2012 Tour winner Bradley Wiggins as the team's dominant force when he topped the podium on the Champs-Elysees 12 months later.
However, Brailsford indicated the likes of Thomas and Bernal now have their esteemed team-mate on the other side of that equation.
"Chris' current contract comes to an end in December and we have taken the decision now not to renew it," he said.
"We are making this announcement earlier than would usually be the case to put an end to recent speculation and allow the team to focus on the season ahead.
"Chris has been with us from the start. He is a great champion and we have shared many memorable moments over the years, but I do believe this is the right decision for the team and for Chris.
"Given his achievements in the sport, Chris is understandably keen to have sole team leadership in the next chapter of his career - which is not something we are able to guarantee him at this point. A move away from Team INEOS can give him that certainty.
"At the same time, it will also give other members of our team the leadership opportunities they too have earned and are rightly seeking."
Four-time Tour de France winner Froome has agreed a "long-term" contract with ISN, tying him to the team until "the end of his illustrious career".
The 35-year-old, who also has a pair of Vuelta a Espana triumphs to his name along with the 2018 Giro d'Italia, will conclude the 2020 season with Team INEOS.
David Brailsford explained Froome's departure from the outfit formerly known as Team Sky was due to the fact he could no longer be assured of sole leadership of a squad that has produced Tour de France winners Geraint Thomas and Egan Bernal in the past two years.
ISN, where his team-mates will include Dan Martin and Andre Greipel, can offer that guarantee.
"I'm really excited to be joining the ISN family," Froome said. "I look forward to challenging and being challenged by their talent and continuing to strive for the success that I've enjoyed up to now.
"ISN's impact on the sport is rapidly expanding, and I'm energised to be along for the ride. I feel we can achieve great things together."
ISN co-owner Sylvan Adams believes Froome can become recognised as the finest rider in the history of the sport during his time with the team.
"This is an historic moment for ISN, Israel, Israeli sports, our many fans all around the world and, of course, for me personally – a moment of enormous pride," Adams said.
"Chris is the best rider of his generation and will lead our Tour de France and Grand Tour squad.
"We hope to make history together as Chris pursues further Tour de France and Grand Tour victories, achievements that would make a serious case for Chris to be considered the greatest cyclist of all time."
It was not until October that last season's event took place, with Ineos Grenadiers rider Tao Geoghegan Hart taking the honours for his first Grand Tour triumph.
However, the Briton's primary target in 2021 is the Tour de France so he will not be wearing the maglia rosa in Milan at the end of the month.
Here is a rundown of everything you need to know about this year's Giro.
THE ROUTE
It is 3,479 kilometres of hard graft from the start in Torino on May 8 to the finish line in Milan 22 days later.
That spans 21 stages, with two rest days, beginning and ending with individual time trials.
In between are some punishing days in the saddle, including seven major mountain stages and brief trips into Slovenia and Switzerland along the way.
All eyes will be on what could be a pivotal day in the mountains on stage 16, which takes in climbs up Passo Fedaia and the Passo Giau in the Dolomites.
The literal high point of the race – though perhaps not at all figuratively for the competitors – will also come on that day atop the Passo Pordoi, at 2,239m above sea level.
THE CONTENDERS
There is little to split Simon Yates and Giro debutant Egan Bernal in the bookies' odds, with stiff competition from elsewhere in the pack.
Bernal is from the rich stock of Ineos Grenadiers' stable and will have the backing of a strong team, as will Team BikeExchange's Yates.
Both have Grand Tour successes under their belts, Bernal winning the 2019 Tour, while Yates prevailed at the 2018 Vuelta a Espana.
Given that Geoghegan Hart was not giving any billing ahead of last year's race, it would be remiss to exclude supposed 'outsiders' from the reckoning.
On that front, Joao Almeida (Deceuninck-QuickStep) and Bernal's team-mate Pavel Sivakov would be two to look out for, while 2020 runner-up Jai Hindley (DSM) cannot be discounted.
PAST WINNERS
2020: Tao Geoghegan Hart
2019: Richard Carapaz
2018: Chris Froome
2017: Tom Dumoulin
2016: Vincenzo Nibali
EXPERT INSIGHT
Tour winner and five-time Olympic champion Bradley Wiggins shed some light on the supposed fragility of Bernal, suggesting the dynamic with Sivakov could prove problematic.
Wiggins favours Yates instead and suggested he could be joined on the podium by fellow Briton Hugh Carthy.
"The air of invincibility around Bernal has now gone after his failure at the Tour last year due to injury," Wiggins told Cyclingnews.
"There are question marks over his form and if he's through the period of being able to get through three weeks of racing without problems for his back.
"But for me this is Simon Yates' moment. He's won the Vuelta and it's been three years since he won that race and he dominated the Giro until Chris Froome did what he did.
"We could have two British riders [Yates and Carthy] on the podium and I think that it's going to be great race, I really do."
Tao Geoghegan Hart finished top of the general classification standings in 2020, and Ganna ensured INEOS hold the maglia rosa once more after day one.
Ganna won the same stage last year – a 15km individual time trial from Monreale to Palermo – and repeated the feat on an 8.6km course in Turin this time around.
The defending time trial world champion, who won four stages in total in the 2020 Giro, went round in a time of 8:47, beating Edoardo Affini (Jumbo-Visma) by 10 seconds.
Affini and his team-mate Tobias Foss had looked well placed after their efforts, but Ganna ultimately had far too much power as he claimed what is the third-fastest individual time trial record in Giro history.
"It was a lot of time waiting in the hot seat at the finish, but I've won the stage, I'm here, and I'm really happy," Ganna, who recorded an estimated average speed of 58.748kmph, said in a flash interview.
"Now, we think about tomorrow, and recovering, because this Giro is really hard. I have this amazing victory."
Ganna is the first rider to wear the pink jersey after stage one of successive Giros since Francisco Moser in 1984 and 1985, while only Diego Ulissi (eight) and Vincenzo Nibali (seven) have won more stages in the event of the riders taking part this year.
Deceuninck-Quick Step riders Joao Almeida, Remi Cavagna and Remco Evenepoel all claimed top 10 finishes, while only a second separated GC favourites Simon Yates (Team BikeExchange) and Egan Bernal (INEOS Grenadiers), who recorded times of 9:07 and 9:08 respectively.
STAGE RESULT
1. Filippo Ganna (INEOS Grenadiers) 8:47
2. Edoardo Affini (Jumbo-Visma) +00:10
3. Tobias Foss (Jumbo-Visma) +00:13
4. Joao Almeida (Deceuninck-Quick-Step) +00:17
5. Remi Cavagna (Deceuninck-Quick-Step) +00:41
CLASSIFICATION STANDINGS
General Classification
1. Filippo Ganna (INEOS Grenadiers) 8:47
2. Edoardo Affini (Jumbo-Visma) +00:10
3. Tobias Foss (Jumbo-Visma) +00:13
Points Classification
1. Filippo Ganna (INEOS Grenadiers) 15
2. Edoardo Affini (Jumbo-Visma) 12
3. Tobias Foss (Jumbo-Visma) 9
King of the Mountains
N/A
Geoghegan Hart had been set to play a supporting role to Geraint Thomas in Italy until the 2018 Tour de France champion suffered a fractured pelvis early in the race.
INEOS were without a number of their other big names amid a packed Grand Tour schedule due to the coronavirus pandemic.
Last year's Tour de France winner Egan Bernal and defending Giro champ Richard Carapaz targeted the Paris event, while the departing Chris Froome - a seven-time winner across all three elite events - entered the Vuelta a Espana.
That left Geoghegan Hart to take centre stage, but he thrived at the Giro to seize a share of the lead with Australia's Jai Hindley heading into the 21st and final stage.
It was the first time in Giro history two riders had been tied heading into the time trial, a 15.7-kilometre ride in Milan.
But Geoghegan Hart ultimately rode to a comfortable victory, finishing 39 seconds clear of his direct rival with a time of 18 minutes and 14 seconds.
"Not in my wildest dreams did I imagine this would be possible when we started out in Sicily almost a month ago," said Geoghegan Hart, who became the fifth British Grand Tour winner.
"All my career I've dreamt of trying to be top 10, top five maybe, in a race of this stature, so this is something completely and utterly different to that.
"I think it's going to take a long time for this to sink in."
INEOS' success did not end there, though, as heavy favourite and time trial world champion Filippo Ganna won the stage in 17:16.
Ganna, making his Grand Tour debut, claimed his fourth stage victory of the Giro after blowing away Victor Campenaerts' early benchmark of 17:48, which remained enough for second place.
STAGE RESULT
1. Filippo Ganna (INEOS Grenadiers) 17:16
2. Victor Campenaerts (NTT Pro Cycling) +00:32
3. Rohan Dennis (INEOS Grenadiers) +00:32
4. Joao Almeida (Deceuninck-Quick-Step) +00:41
5. Miles Scotson (Groupama-FDJ) +00:41
CLASSIFICATION STANDINGS
General Classification
1. Tao Geoghegan Hart (INEOS Grenadiers) 85:40:21
2. Jai Hindley (Team Sunweb) +00:39
3. Wilco Kelderman (Team Sunweb) +01:29
Points Classification
1. Arnaud Demare (Groupama-FDJ) 233
2. Peter Sagan (Bora-Hansgrohe) 184
3. Joao Almeida (Deceuninck-Quick-Step) 108
King of the Mountains
1. Ruben Guerreiro (EF Pro Cycling) 234
2. Tao Geoghegan Hart (INEOS Grenadiers) 157
3. Thomas De Gendt (Lotto-Soudal) 122
Former rider Portal passed away on Tuesday aged only 40, having reportedly suffered a heart attack at his home in Andorra.
Following the news, INEOS announced on Wednesday the cycling team would be out of action until the Volta a Catalunya later this month.
They will not compete in the Strade Bianche, Paris-Nice, Tirreno-Adriatico, Milan-San Remo, Nokere Koerse or Bredene Koksijde Classic, although some races are in doubt due to the coronavirus.
The virus has seen a decree in Italy that means the public cannot attend sporting events for 30 days, with Serie A football matches to be played behind closed doors.
Organisers of the Tirreno–Adriatico and Milan-San Remo races confirmed updates would follow in the coming days after meetings with the authorities, with 2502 cases and 80 deaths in Italy.
INEOS highlighted both Portal's death and the virus concerns in a statement that listed reasons for the team's temporary absence.
Team boss Dave Brailsford said: "This is a uniquely sad moment for everyone at the team. We have lost someone we all loved very much and are all grieving for Nico.
"I would like to thank everyone for their messages following the tragic news yesterday. They have really meant a lot to us all as we try to come to terms with this terrible news.
"Nico meant the world to us as a team and it is genuinely touching to know how much he also meant to everyone else across the sport.
"We are taking this decision to put a temporary pause on racing today because of this unique set of circumstances we are facing. It is right for the team given what has happened but I also believe it is in the best interests of both cycling and the wider public.
"Cycling is a uniquely mobile sport. We have a duty of care both to our riders and staff but also to the people living in the areas where we race.
"We do not want to be in a position where our riders become potentially infected or quarantined on race as has already happened.
"Equally we are acutely aware that these are difficult times for all local health services and we do not want to put any additional pressure or burden whatsoever upon them when all their focus should rightly be on their own local population."
Mitchelton-Scott have likewise withdrawn from racing for the time being, with UAE Team Emirates, Groupama-FDJ, Cofidis and Gazprom-RusVelo still quarantined after the final two stages of the UAE Tour were cancelled.
Former rider Portal reportedly suffered a heart attack at his home in Andorra.
The popular Frenchman ended his racing career in 2010 due to cardiac arrhythmia, but remained with Team Sky after retiring.
Portal oversaw Chris Froome's four Tour de France triumphs and played his part in Egan Bernal winning the yellow jersey last year after Team Sky became Team INEOS.
A Team INEOS statement said: "It is with the greatest sadness that we announce the passing of our much loved team-mate, colleague and friend Nico Portal who died suddenly this afternoon at his home in Andorra.
"We are all overcome with grief at this terrible news and would ask everyone to respect the family's privacy at this difficult time.
"RIP Nico - your spirit will always be with us on the road and you will forever be in our hearts."
Froome was among the riders to pay tribute to Portal.
He tweeted: "My thoughts are with Nico's wife and children tonight. He was the kindest, happiest guy I knew and always lived life to the fullest. Rest In Peace Nico."
Portal competed in seven Grand Tours and won a stage at the 2004 Criterium du Dauphine before such a successful career off the bike.
