The 28-year-old passed a medical and signed a four-year contract with an option for a further season, after completing a 40-million-euro move from cash-strapped Valencia.
He had a buy-out clause of 200 million euros, Barca said on their website.
Villa will be leading the line for Spain at the World Cup finals next month, along with new Barca team mates Xavi, Andres Iniesta, Gerard Pique, Carles Puyol, Pedro, Sergio Busquets and Victor Valdes.
"One of the many reasons that helped me make my decision to go to Barca, once Valencia said they wanted to sell me, was the friendship I have with many of them (the players)," Villa told reporters.
"I know I won't have any problems because many of them have already helped me to become a Barcelona player."
The quietly-spoken Asturian added: "I am proud that Barca returned to try and sign me (after an unsuccessful attempt last season). I have always been clear about where I wanted to go."
Barca's sports director Txiki Begiristain said Villa's arrival did not threaten Swedish forward Zlatan Ibrahimovic's future at the club.
"David is an extraordinary number nine but can also play out wide, he is completely compatible with Ibrahimovic," Begiristain told reporters.
"The season is very long, and we need forwards of great quality, and now we have covered every type of profile. There isn't a perfect XI and coach Pep Guardiola will decide in each game."
With World Player of the Year Lionel Messi a definite up front and youngsters Pedro and Bojan Krkic pushing for places the player most likely to be moving on is France striker Thierry Henry.
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