The attacker, who left United permanently in 2015 to join Fenerbahce has a clause in his contract that says he can leave for €8.5m but the stipulation expires on June 30.
“Nani will play for Valencia next season,” said Fenerbahce president Aziz Yildirim told AMK Sport (via Marca).
Nani scored eight goals in 27 appearances in the Turkish top flight last season, and has been in impressive form throughout his time since leaving Old Trafford.
The Portugal winger, who has started every game for his national side at Euro 2016 alongside Cristiano Ronaldo, also added eight assists in the 2015/16 Turkish Super Liga campaign.
The winger has really impressed at Euro 2016, where he has scored two goals in four appearances, and if he continues this form next season for Valencia, his €8.5m transfer fee will seem like a bargain for the 29-year-old.
There is a new era being ushered in at Valencia, with former assistant Pako Ayesteran taking over as coach following the sacking of both Nuno Esperito Santo and Nani’s former Old Trafford teammate Gary Neville last season.