The Portugual international penned a three-year deal with the Turkish side on Monday after Fenerbahce agreed a £4.5m deal to sign the 28-year-old forward from United.
Thanks to all my colleagues, to all staff and management structure, thank you Sir Alex Ferguson!
Nani helped the Red Devils to win four Premier League titles and the Champions League during an eight-year stay at the 20-time English champions.
However, he was sent out on loan to former club Sporting Lisbon last season following the appointment of Louis van Gaal.
Nani wrote the following message on his Instagram page: “I leave Manchester with many titles and many memories, I want to thank all the people who helped me on this journey and wish you all the luck and success!
“Thanks to all my colleagues, to all staff and management structure, thank you Sir Alex Ferguson!”
Nani scored 25 goals in 147 Premier League appearances during his United career.
The Portuguese star was named in the PFA team of the year as he played a pivotal role in United’s Premier League title success in 2011.
The Fenerbahce signing netted 40 times in 230 games but failed to emulate the performance of his compatriot Cristiano Ronaldo at United.
MORE: Man United latest news
MORE: Arsenal latest news
MORE: Chelsea latest news
MORE: Liverpool latest news