The former Manchester United forward has joined Venezia on a small 18-month contract, the Serie A club said on Friday.
The 35-year-old was a free agent after his contract with US Major League Soccer team Orlando City expired earlier this month and moved to Italy for the second time in 2017-18 after spending a year on loan at Lazio.
Little is known for his eight years in England with United, where he won four Premier League titles and the Champions League in 2008.
Nani scored 24 goals in 112 games for Portugal, and participated in the 2014 World Cup and the 2008, 2012 and 2016 European Championships, playing in the 2016 final when he beat France.
This is Venezia’s second signing in the January transfer window after Bayern Munich midfielder Michael Cusons. They are 17th in the Serie A standings after 20 games, well above the relegation zone with one game over their main rivals.