The 21-year-old joined Barcelona from Sporting Braga at the start of last season and made 42 appearances across all competitions in his debut campaign at the Camp Nou, though he started most of those games from the bench.
Wolves have the option to make Trincao’s move permanent at the end of the season.
Trincao joins a strong Portuguese contingent at Molineux which includes new manager Bruno Lage as well as teammates Joao Moutinho, Pedro Neto, Ruben Neves, Nelson Semedo and Rui Patricio.
"We've watched him a lot, especially over the last couple of months, so he's been on our radar for quite a while," said Wolves technical director Scott Sellars.
"He's got loads of quality - signing for Barcelona from Braga shows what potential he's got. He's 21 and has played quite a lot of games in La Liga, so we think he's ready for the Premier League.
"He's a player who drifts past people and he has a great change of direction when he's moving with the ball. He has great speed over two or three yards, to change direction and get away from people, can score and create, and is an exciting player."
Trincao has six caps for Portugal but was not part of their EURO 2020 squad.
"We have a large Portuguese contingent, and they look after each other well, but are also integrated in the whole group," Sellars added.
"They're really hard-working, with a good mentality, so I'm sure he'll integrate well and settle in quickly.
"With the manager's Portuguese background, he knows him and speaks very highly of him, so he's a player we're very excited to be bringing to the club."
