World Cup winner Ozil, once Arsenal's record signing, had been excluded from Mikel Arteta's first-team plans this season and departs after seven and a half years with the Premier League club.
The former Germany midfielder was under contract until the end of the current campaign but reached an agreement for an early termination, clearing him to sign elsewhere.
Fener have now confirmed the arrival of Ozil, with Arsenal announcing the playmaker's departure on their official website.
In a statement in the Gunners' announcement, Ozil said: "I'd like to thank the club for this amazing journey over the past seven-and-a-half years.
"The support I have felt from the team and fans during my time here has been truly incredible and something I will always be grateful for.
"Together we won trophies for the first time in years and created memories that will last a lifetime.
"The Arsenal fans will forever remain in my heart. I'd like to thank Edu Gaspar for helping bring about a professional and dignified solution in the past few days, and I wish everyone at the club the best in their attempt to continue to bring Arsenal back to the top, where we belong."
Having joined from Real Madrid in September 2013, Ozil made 184 Premier League appearances for Arsenal, scoring 33 goals and contributing 54 assists.
He was a key part of Arsene Wenger's squad that finished second in the 2015-16 Premier League season, while he also started in the FA Cup final triumphs in 2014, 2015 and 2017.
However, the 32-year-old had increasingly become a peripheral figure in recent years, initially under former Gunners boss Unai Emery before being left out entirely by Arteta.
His final Arsenal appearance came on March 3, 2020, when he played 89 minutes in a 1-0 win over West Ham at Emirates Stadium.
Although he was twice named on the bench when the 2019-20 season resumed after the coronavirus-enforced break, the 32-year-old was an unused substitute against both Brighton and Hove Albion and Southampton in June.
"Mesut's achievements at Arsenal are undisputed," Arteta said. "It was a privilege to play alongside him and, more recently, coach him.
"His creativity and vision led to many goals during his time in the Arsenal shirt. Mesut was at the heart of many great moments for this club over the years, including those three FA Cup final wins.
"These successes will always be part of our history. We thank Mesut and wish him all the best with Fenerbahce."
Goalkeeper Rustu spent much of his club career at Fenerbahce, including a loan stint with the Turkish Super Lig giants during a three-year stay at Barcelona.
A star of the 2002 World Cup, Rustu played just seven times for Barca - all within the 2003-04 season - but retired aged 39 in 2012 with 120 international caps to his name.
The 46-year-old's wife Isil posted on her Instagram page on Saturday to inform fans of her husband's diagnosis.
"I would like to give you more positive news while sharing the truth in the most transparent way, but I'm sorry to say that my husband Rustu is hospitalised with the diagnosis of COVID-19," she wrote.
"We are shocked by the rapid symptoms that developed suddenly when everything was normal. These are critical and difficult times.
"May Allah give emergency relief to all patients, including my dear husband.
"My only request is that people can be a little more conscientious and respectful in the process. In the tests we have done, my daughter and son were negative and only my husband was positive.
"For this reason, we are at home while he's in hospital, and we are not allowed to see him. In fact, this is the most difficult part, not being able to be with him.
"Allah is great and is entrusted to him and the Turkish doctors. I hope this will pass."
After being held by both Twente and Porto, United travelled to Turkiye requiring a win to ease the mounting pressure on boss Erik ten Hag.
However, they were unable to hold on after Christian Eriksen gave them an early lead, with Youssef En-Nesyri heading a second-half equaliser to lift Fenerbahce to five points from three Europa League matches.
Fielding a strong lineup, United went on the front foot early on and were rewarded after 15 minutes, Eriksen firing home after being fed by Joshua Zirkzee on the edge of the area.
Marcus Rashford went close to doubling United's lead after cutting in from the left-hand side, but the Red Devils were indebted to Andre Onana for preserving their lead in the 39th minute.
Onana got down to his right to claw En-Nesyri's header away, then sprung to his feet to tip the Moroccan's second effort away in an incredible double-save.
En-Nesyri was not to be denied four minutes after half-time, though, getting between Victor Lindelof and Lisandro Martinez to direct Allan Saint-Maximin's cross past Onana.
Fenerbahce wanted a penalty when Manuel Ugarte collided with Bright Osayi-Samuel, with Mourinho sent to the stands for his furious reaction to the challenge, but they largely failed to trouble United's goal after drawing level.
The visitors were also unable to find a winner, Rashford missing their clearest chance when he could only prod Diogo Dalot's inviting cutback wide.
Data Debrief: Six of the worst for United
United have now gone six games without victory in European competitions, drawing four and losing two, their longest such run since an identical streak between 1980 and 1983.
They have won just one of their last 11 matches in Europe overall and are now without a win in their last three trips to Fenerbahce, losing two and drawing one.
There was to be no statement victory for Mourinho, either. He has only won two of his last 18 matches against teams he has previously managed, drawing five and losing 11.
Christian Eriksen had given the Red Devils the lead in the first half, but they were pegged back by Youssef En-Nesyri four minutes after the break in their 1-1 draw.
United have now won just one of their last eight games in Europe when scoring first (D5 L2), drawing each of their last four games when going 1-0 up.
It was a third consecutive stalemate in the Europa League for United, who were indebted to their goalkeeper as he made three saves, including an incredible double stop to keep his side in the lead at half-time, but he was left frustrated by the result.
"It is a big disappointment for me and the fans, for the club, as a Manchester United player you have an obligation to try to win," Onana told TNT Sports.
"We didn't win, but at least we didn't lose. Not happy, of course, but we move on, take responsibility and go again.
"We conceded an early goal in the second half, we had to show character, and I think that is what we did. We didn't win, but I thought we were better than them."
United were without a number of players through injury or suspension, with Bruno Fernandes one of those to miss out after being sent off against Porto.
In fact, United have failed to win any of their last five away games without their captain in all competitions (D2 L3), with the Red Devils scoring just two goals in total across those five matches.
Despite the result, Erik ten Hag was keen to take the positives from a game which also saw them lose Antony, who came on as a second-half substitute, to injury.
"We've shown we are a team which is hard to beat," said Ten Hag. "We can take confidence and take it into the game against West Ham.
"We have to win, and we came in the position to win. We created the chances, but we have to be killing more. We let the opponent get away with a point.
"[Antony's] training performances are that good that he deserved to come on. When you have to come off so quickly, that is really sad to see. Hopefully, it's not too bad, we have to wait 24 hours for what the assessment is."
The club fielded a starting line-up entirely of youth team players for the final against their arch rivals, with their first-team stars training back in Istanbul ahead of Thursday’s Europa Conference League tie at Olympiacos.
However, only one minute and 41 seconds was played at the Sanliurfa GAP Stadium when the Fenerbahce players left the field shortly after Mauro Icardi’s strike with 50 seconds on the clock.
Galatasaray celebrated wildly with their fans after victory was confirmed, while their opponents did not even acknowledge that the final took place on Sunday evening on their social media channels.
In a statement released on the club’s official website, Fenerbahce president Yildirim Ali Koc said: “Our rebellion today, our stance in the Super Cup, is not only about the date of the match or what happened in the last away match.
“It is time for a ‘reset’ for Turkish football. We are in a period when the swamp must be drained and Turkish football must rebuild itself. There’s no need to reinvent the wheel.
“I hope that the justified rebellions of our club and the actions we decided to take out of necessity will ignite the cleansing process that needs to be done.
“This is the time when impartiality, fair competition and sporting ethics must come to the fore.”
Fenerbahce previously announced their intentions to field a team of academy players for the final due to their grievances against the Turkish football governing body.
Fenerbahce players were attacked by Trabzonspor fans after their 3-2 away victory on March 17, which resulted in the Super Lig club receiving a six-match spectator ban and a fine of £74,105.
Trabzonspor appealed against the sanctions following the incident, where 12 people arrested, and were earlier this week reduced to a stadium ban of four games and £11,066 fine.
As a result, Fenerbahce held an extraordinary general meeting with their members where they agreed to request for the Super Cup final to be rearranged once again with a foreign referee, which was rejected by TFF.
The final was originally slated for December 30 last year in Riyadh, Saudi Arabia, but was postponed after both teams planned to wear t-shirts of Mustafa Kemal Ataturk – the original founder of Turkey – in the build-up.
The members voted for the club not to participate in the Turkish Cup for the next two seasons, unless fielding an academy line-up, while also calling for action from FIFA and UEFA against the governing body.
Hiddink declared in a television interview that he had decided to quit as boss of Curacao and would not return to football.
The Dutch great told SBS 6: "Lately, with COVID, I haven't worked much. Coincidentally I was talking with the president of the Curacao federation and we came to the conclusion it was better that I stop for a while, because they are going in a new direction.
"But I'm going to stop totally. Am I going to do a Advocaat. No, no."
That was a reference to his fellow veteran coach Dick Advocaat, who was expected to retire after leaving Eredivisie giants Feyenoord last season but instead took on the job of coaching Asian nation Iraq.
Hiddink began his career at PSV and had two spells with the Eindhoven club, from 1987 to 1990 and 2002 to 2006, winning three Eredivisie titles in each successful stint.
His PSV side won the old European Cup in 1988, beating Benfica on penalties in Stuttgart following a goalless draw, clinching a treble after already landing the domestic league and cup titles.
He twice led teams to World Cup semi-finals – the Netherlands in 1998 and South Korea in 2002 – and helped Australia reach the second round of the 2006 tournament.
His Russia team reached the Euro 2008 semi-finals, where they lost 3-0 to Spain, and he had his first short spell as Chelsea interim manager while still in that national team job, helping the Blues win the 2009 FA Cup.
Hiddink was not a success at Madrid, failing to complete the 1998-99 season before he was sacked. He managed one trophy while at the Santiago Bernabeu, helping Madrid beat Vasco da Gama in the Intercontinental Cup.
A long career as a head coach also took in jobs at Valencia, Real Betis, Turkey, Fenerbahce and Anzhi Makhachkala.
Hiddink had a brief and unsuccessful second stint as Netherlands boss, then succeeded Jose Mourinho at Chelsea in December 2015 and helped the team recover from a shocking start to their title defence season, but that was just a half-season tenure.
A year as China Under-21 coach followed, and then the curtailed spell as Curacao boss, his final act, barring a change of heart.
Defending champions Galatasaray, Fenerbahce and Besiktas have dominated Turkish football – the three Istanbul giants winning 54 league trophies between them.
But the powerhouse trio were unable to compete with fellow Istanbul outfit Basaksehir this season.
Basaksehir – formed in 1990 – became just the sixth club to win the Super Lig since the league's inception in 1959 thanks to Sunday's victory and second-placed Trabzonspor's 4-3 loss to Konyaspor.
Boasting the likes of former Real Madrid and Manchester City forward Robinho, Gael Clichy, Martin Skrtel and Demba Ba, Okan Buruk's Basaksehir are seven points clear atop the table with one match remaining.
Basaksehir are also on track to meet Premier League giants Manchester United in the Europa League.
The Turkish champions hold a 1-0 lead over Copenhagen heading into the second leg of their last-16 tie, while United defeat LASK 5-0 prior to the coronavirus pandemic.
The Europa League is set to resume next month following the enforced break due to COVID-19.
The Turkish side earned a share of the spoils in Istanbul, where Youssef En-Nesyri was on target in the second half to cancel out Christian Eriksen's earlier effort.
Although, it could have been more for the hosts, who saw a penalty appeal waved away after Manuel Ugarte collided with Bright Osayi-Samuel.
Mourinho was sent to the stands for his furious reaction to the challenge, and the former United boss lifted the lid on his interaction with French official Turpin later in the referee's room.
"I watched the incident back, and I don't want to speak about it," he told TNT Sports.
"He told me something incredible. He told me that at the same time, he saw the action in the box and my behaviour. I congratulate him, it's incredible - his peripheral vision!
"He had one eye on the penalty situation and one eye on my behaviour on the bench – that's why he's one of the best referees in the world!"
Nevertheless, Mourinho was full of praise for his players following their performance, after they took their points tally to five after the opening three matchdays.
"They got a point against us, not us against them," he added. "We played amazingly. I told the players: 'if we play like this in the Turkish league, we will destroy every single team'.
"The Premier League has more quality, more intensity, more pace, more everything.
"In England, you'll probably talk about one or two players from United who didn't play. You don't know how many of our players didn't play, we had injuries. We had to solve an amazing puzzle.
"My boys played an amazing match. We had a phenomenal performance. My goalkeeper didn't make a save."
The 92-cap Germany international, who won the World Cup with his country in 2014, also represented Schalke, Werder Bremen, Fenerbahce and Istanbul Basaksehir during his 17-year career.
Ozil was under contract with Turkish side Basaksehir until the end of the season, but he has called time on his playing career due to a number of injury issues.
"After thoughtful consideration, I'm announcing my immediate retirement from professional football," he wrote in a statement on his personal Twitter account on Wednesday.
"I've had the privilege to be a professional football player for almost 17 years now and I feel incredibly thankful for the opportunity.
"But in recent weeks and months, having also suffered some injuries, it's become more and more clear that it's time to leave the big stage of football."
Ozil started his career with Schalke before moving to fellow Bundesliga side Werder Bremen, where his impressive form across three seasons led to a move to Madrid.
In three campaigns at the Santiago Bernabeu, the German playmaker won a LaLiga title, a Copa del Rey and the Supercopa de Espana.
He joined Arsenal in a big-money deal in September 2013 and was arguably the best number 10 in world football for a period.
Indeed, the 146 chances Ozil created in 2015-16 remains the most ever in a single Premier League campaign.
After seven and a half years in north London, during which time he won four FA Cups, Ozil joined Fenerbahce on a free transfer after his Arsenal contract was terminated.
Ozil spent two largely unsuccessful seasons with Fener before making the switch to Basaksehir, where he had been restricted to just four league appearances this season.
"It has been an amazing journey filled with unforgettable moments and emotions," Ozil added in his statement.
"I want to thank my clubs – Schalke 04, Werder Bremen, Real Madrid, Arsenal FC, Fenerbahce, Basaksehir and the coaches who supported me, plus team-mates who have become friends.
"Special thanks must go to my family members and my closest friends. They have been a part of my journey from day one and have given me so much love and support, through the good times and the bad.
"Thank you to all my fans who have shown me so much love no matter the circumstances and no matter which club I was representing.
"Now I'm looking forward to everything that is in front of me with my beautiful wife, Amine, and my two beautiful daughters, Eda and Ela – but you can be sure that you will hear from me from time to time on my social media channels. See you soon, Mesut!"
At international level, Ozil started all seven of Germany's matches in their triumphant World Cup 2014 campaign.
He scored 23 goals in 92 appearances, the most recent of those caps coming against South Korea at the 2018 World Cup.
Sofyan Amrabat scored a 102nd-minute winner as the Istanbul giants sealed a dramatic 3-2 victory to remain within five points of Turkish Super Lig leaders Galatasaray.
Despite the result, Mourinho was enraged by Trabzonspor receiving two penalties following VAR reviews, also claiming his team should have had a spot-kick of their own ahead of Amrabat's winner.
"I blame the Fenerbahce people that brought me here," Mourinho said after the game. "They told me only half of the truth.
"They didn't tell me the whole truth because if they told me the whole truth, I wouldn't come. But with half of the truth and my boys, we fight opponents and the system."
Mourinho then took aim at Karaoglan and suggested Fenerbahce did not want him to officiate their future games.
"The man of the match was Atilla Karaoglan," he added. "We didn't see him, but he was the referee.
"The referee was just a little boy that was there on the pitch, but the referee was Atilla Karaoglan. He goes from the invisible man to the most important man in the match.
"I think I am speaking on behalf of every Fenerbahce fan – we don't want him again. We don't want him as a VAR. We don't want him on the pitch but, on the VAR, even less.
"He was alert to give the two penalty decisions which the referee didn't give and then he was having Turkish tea when it was a clear penalty for us and he didn't give it."
Ten Hag faces one of his Old Trafford predecessors on Thursday when United visit Mourinho's Fenerbahce in the Europa League.
The current United boss is a man under pressure after a difficult start to the season, despite delivering silverware in each of his first two seasons in England.
Those were the Red Devils' first trophies since Mourinho was in charge, with the Portuguese leaving Manchester in 2018 and subsequently working at Tottenham, Roma and now Fenerbahce.
Fener are now fourth in Turkey's Super Lig, eight points off the pace, albeit with a game in hand.
But Ten Hag has faith in Mourinho, just as he does in his own ability to turn United's fortunes around.
"Mourinho and I, we won a lot of trophies the last years, but you have to prove yourself every year," the Dutchman said. "When you don't win, we are always under criticism.
"We know that we are experienced enough. Professional football is about winning games, and when you don't win, the criticism is coming.
"But at the end of the day, it's about how you are at the end of the year.
"Mourinho is so experienced, he will lead this team to its best form, he will be successful and so will we.
"We are convinced we are in the right direction, that we follow the right path and we will achieve what our targets are."
Fenerbahce fell into the Europa League after losing a Champions League qualifier to Lille but have at least earned four points from their first two matches in Europe's secondary competition.
United have made hard work of winning two points across the same period, their European form no more impressive than domestic results, which have them 12th in the Premier League.
Going back to last season's miserable Champions League campaign, United are winless in five European matches, their worst run since the 1980s.
"Man United didn't win in Europe [since Mourinho's Europa League win] and it's also for us a target, what we want to achieve, and we have a big opportunity this season," Ten Had added.
"We have the quality, we have to win games. It's a new set-up, we are two games under way, we have two points, we know what we have to do and win games.
"This season we just started, we have two draws. First season, I think we won a lot of European games. Last season, obviously it was for domestic and also in Europe a difficult journey.
"But we are confident, we are confident we are capable to do this, to win games in the Premier League and in Europe."
Mourinho's Fenerbahce welcome United on matchday three, with both sides aiming to maintain their unbeaten starts to this season's competition.
The Red Devils, who have opened with two draws against Twente and Porto, ended their five-game winless streak across all competitions with a 2-1 victory over Brentford on Saturday.
United's difficult form has seen the pressure intensify on Erik ten Hag. But Mourinho, who was in charge at Old Trafford between 2016 and 2018, thinks it is only a matter of time before things click into place for the Dutchman.
"If I have to say now which are the two biggest candidates to win the Europa League, I think it's easy - Manchester United and Tottenham," he said.
"The Premier League has a different level of quality, intensity, pace, tactical culture - a different level of everything. [On Thursday] I think we are going to play against one of the two strongest teams.
"They have a better team than their results are showing. I studied them the maximum I could. We watched everything in the Premier League, [and previous Europa League games against] Twente and Porto - there is work there. They will succeed sooner or later."
Mourinho, who oversaw a second-place Premier League finish with United during the 2017-18 season, also cheekily asked if he would be entitled to a winner's medal, due to potential charges against Manchester City for allegedly breaching financial rules.
If found guilty of the charges dating from 2009 to 2018, City could face severe punishment, including being stripped of titles.
One of those could be from the 2017-18 season, when Pep Guardiola's side became the first team to finish a Premier League campaign with 100 points, 19 ahead of Mourinho's United in second place.
"I think we still have a chance to win that league!" Mourinho joked. "Maybe, they punish Manchester City with points [deducted], we win that league, they have to pay me the bonus, and give me the medal."
