Nani has signed a two-year deal with Sporting CP after agreeing to return to his former club from Valencia for an undisclosed fee.
The 31-year-old winger joined Los Che two seasons ago from Fenerbahce but spent last season on loan at Lazio, where he featured in just 18 Serie A appearances.
Nani began his career with Sporting before a 2007 move to Manchester United, and spent the 2014-15 campaign on loan at the Lisbon-based club, where he has netted 23 times in 113 matches.
The Portuguese winger, who helped his nation to the European Championships in 2016, was valued at around €5m and was under contract at the Mestalla until 2019.
Earlier this week, Nani hinted to news agency DHA that he would be returning to Fenerbahce: “Fenerbahce have not been a champion in recent years. I want to contribute to winning the title and being a part of it would be a real joy, obviously, right now I'm talking to the club.
“It would be great to be back in front of the Fenerbahçe fans. I want to be part of the team that wins the league.”