Trincao has been in Lisbon for days to seal his signing for Sporting and on Wednesday, it was made official.
Barcelona announced the deal, just after they said they were bringing in Raphinha from Leeds United.
Trincao goes on loan to Portugal and the club will have an option to buy once the loan is over.
He was out on loan to Wolves last season in the Premier League.
Trincao featured 42 times for Barcelona, although often not for 90 minutes. He goes back to his homeland to try and win the league there with Sporting, who won it in 2020-21.