"This is an exciting day for our organisation,” Luiz Muzzi, Orlando City's executive vice-president of Soccer Operations, said in a statement on the club website.
"Nani brings tremendous experience to our roster. He’s a dynamic winger with quality abilities to move and cross the ball, impact games and lead the offensive play.”
Nani made his Premier League debut as a substitute for Wayne Rooney on Aug. 12, 2007 and remained with United until 2014, making 230 appearances in all competitions, scoring 41 goals.
In 2014, Nani returned to Sporting on loan and has since played for Fenerbahce, Valencia and Lazio before returning to the Portuguese club in July last year, playing 28 games and scoring eight times.
"Sporting Clube de Portugal... appreciates the services provided and wishes Luis 'Nani' the greatest personal and professional success," Sporting said on their website.
Nani helped Portugal win the 2016 European Championship and was a member of their 2014 World Cup squad. He has been capped 112 times, scoring 24 goals for his country.
(Reporting by Steve Keating in Toronto; Editing by Ken Ferris)
