Belarus midfielder Aleksandr Hleb signed a four-year contract with Barcelona to complete his move from Arsenal, the Spanish Primera Liga club said on Wednesday.
The 27-year-old, a long-term target for Barcelona, flew to Spain on Wednesday to take his medical, arriving just after the club had agreed to sell Brazilian Ronaldinho to AC Milan.
"Hleb was a priority for us. He is extremely versatile with great footballing skills," Barca coach Pep Guardiola told a news conference.
Barca said Hleb moved for 15 million euros ($23.87 million), with a further two million payable dependent on results and that he would join up with the rest of the squad for pre-season training straight away.
Hleb becomes the Catalan side's fifth signing of the close season as they continue to rebuild the team under new coach Guardiola after two years without silverware.
They have already landed Uruguay defender Martin Caceres, former youth team defender Gerard Pique, Brazil full back Daniel Alves and Mali midfielder Seydou Keita.
After finishing third in the league last season they have a Champions League third qualifying round tie to play next month.
Hleb, who had made it clear he wanted to leave Arsenal despite having two years left on his contract, will help add to Barca's attacking potential, linking up with former team mate Thierry Henry.
Barca have said that to complete their squad they wanted an attacking midfielder, a wide player and a number nine, and Hleb can play in either of the first two roles.
Arsenal striker Emmanuel Adebayor has been linked to the club as a possible front man to replace Samuel Eto'o, who has been told he is surplus to requirements.