"Today ends one of the most beautiful stages of my career," the 30-year-old said on social media.

It is understood United will receive 10m euros (£8.62m), with an additional 5m euros (£4.31m) in potential add-ons.

"I lived the dream of wearing the shirt of one of the biggest clubs in the world," added Fred.

"Going through ups and downs, I leave with the conviction that I always gave my best during all training sessions and games.

"It was five years of a true dream for me and my family. I will be forever grateful for the opportunity. Forever a Red!"

Fred was told that he is unlikely to play a significant role in United manager Erik ten Hag's squad this season.

Fenerbahce's Istanbul rivals Galatasaray and Premier League side Fulham were among other clubs to have expressed an interest in the player.

Fred's contract at Old Trafford had been scheduled to expire next summer.

He made 56 appearances for United last season and scored six goals as he helped Ten Hag's side finish third in the Premier League to secure a return to the Champions League.

Overall, he played 139 times for the club in the top flight, scoring eight goals and providing seven assists.

"I am very happy to come to Turkey's biggest club with such a great history. I want to be a part of this history too," Fred told Fenerbahce's website.

"My first impressions are very good and positive. Everyone at the club made me feel very welcome. I was extra happy for that too.

"I also want to play big by doing my best, win all the trophies and contribute to all successes. Of course, I want to make the fans happy.

"Now I will play for Fenerbahce fans on this field here. I cannot wait for this. Fenerbahce fans started to support me even before I came here. I will do my best. Let no one doubt that.