Malcom insisted he always wanted to sign for Barcelona after the Brazilian winger was set to join Roma.
With Malcom set to board a flight to Rome ahead of the transfer, LaLiga champions Barca made a last-ditch bid which was accepted by the French team and the in-demand star ended up at Camp Nou.
Speaking after he was presented by Barca in Portland on Thursday, Malcom said: "I always wanted to go to Barcelona.
"I was always calm. My agents have been in charge of this whole issue.
"It was an opportunity to play for Barcelona and here I will play with the best players in the world. I am very happy to be able to be at a team like this.
"It's very difficult to come to Barcelona, but I am going to give all I have to do a good job. I am very happy in my heart, I am realising a dream that I have had since childhood."
Malcom, who also reportedly attracted interest from Manchester United, Arsenal, Tottenham and Paris Saint-Germain, scored 12 goals in Ligue 1 last season.
"We saw that he had the Barcelona profile," Barca sporting director Eric Abidal said.
"He is a left-footed player who can play on both wings, while he can also play as an attacking midfielder. He has a big future ahead of him."