Barca have made the 24-year-old their seventh summer signing and he was at the Nou Camp on Friday finalising his medical and preparing for his official unveiling.
The full-back, who will cost up to 5.5million euros depending on appearances, was a surprise target for the Catalan club and is unlikely to feature in Sunday's Primera Division trip to Villarreal.
But simply being aboard represents a lifetime's ambition for player.
"This is the pinnacle for me - this is everything I could wish for," he told Barca TV upon his arrival in the city.
"I am so happy to be able to represent this club. I want to thank everyone involved in me coming here and I just hope I can return their confidence in me on the pitch.
"I want to learn because the game here is different to how we play in Brazil."
Although Douglas admits he is ready to experience plenty of differences at Barcelona, at least one of his new team-mates is a familiar face.
He added: "They are all big stars here, I've seen them play of course and I've played against Neymar in Brazil - he is a sensational player and a great representative for the Brazil team."
Barca were unsurprising 3-0 winners over Elche in their season opener last week, with Villarreal also claiming three points with a 2-0 success at Levante.
The Yellow Submarine followed that up with a 4-0 win over Astana at El Madrigal in the second leg of their Europa League play-off.
Having also won 3-0 away from home, they now boast a record of nine goals scored and none conceded this season.
Reflecting on the psychological boost afforded by the European triumph, manager Marcelino Garcia Toral said: "It is very important for the entire group to be back into Europa League and it is a nice challenge for everyone.
"We are very happy to be in the group stage and playing as well as the team have done so far.
"All the players have been at a high level and therefore have achieved great results and you cannot ask for more."