The 31-year-old was unveiled in front of over 10,000 club supporters at the Sukru Saracoglu stadium on Tuesday.
“I promise you one thing – I will do everything in my power to help Fenerbahce win as many trophies to make you happy. Let’s do it together,” Van Persie said.
Man United signed Van Persie from Arsenal for £24m in 2012 and he scored 26 goals to help the Red Devils win the Premier League title in his first season.
Robin Van Persie Svored 58 Goals for Man United Between 2012 and 2015. Image: Fenerbahce.
Van Persie also said he has spoken to other clubs about a move and that he had “no hard feelings” against Manchester United.
“It’s part of football, it’s part of life. I had a good moment with the players the day before I came to Istanbul so that was special,” he said.