Having managed to keep his signing under wraps, Trincao comes in having played 42 times for Barca.
The La Liga giants paid Portuguese side Braga around £27million for him last year, and Wolves could land the 21-year-old for a slightly lower sum.
He is the club's second summer signing after Colombian centre-half Yerson Mosquera, and technical director Scott Sellars said: "He’s a really exciting player.
"It’s an area we’d like more competition, in terms of wide players. I think the fans are going to enjoy watching him play, he drives with the ball well and has good creativity.
“We’ve watched him a lot, especially over the last couple of months, so he’s been on our radar for quite a while. 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 scored three times for Barcelona last season and also has six Portugal caps to his name.
“He’s a player who has good experience, a good pedigree in terms of club and international games he’s had, so he’s certainly a player who is going to add quality to the squad," added Sellars.
“We have a large Portuguese contingent, and they look after each other well, but are also integrated in the whole group. 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.”
Wolves are also due to wrap up the permanent signing of left-back Rayan Ait-Nouri from French club Angers for £10m.