The Brazil international made 67 appearances across all competitions for Leeds during his two-season spell at Elland Road.
Raphinha joined the West Yorkshire outfit from Rennes in October 2020. The Premier League club spent £17million on his signature as the player scored 17 goals.
Arguably his biggest contribution came on the final day of last season, as his opener ultimately helped Leeds to a 2-1 victory over Brentford - a result which helped the club avoid relegation.
In a statement, the club said: "Leeds United can confirm Raphinha has today completed a transfer to FC Barcelona for an undisclosed fee."
Leeds added: "We would like to place on record our sincere gratitude to Raphinha for his effort and contribution whilst at the football club.
"He showed unquestionable commitment and professionalism until the very end of his time at Elland Road and his celebrations at the Brentford Community Stadium will live long in the memory.
"Everyone at Leeds United would like to wish Raphinha the very best for the future and hope he enjoys great success at the Nou Camp and throughout his career."
Leeds have signed six new players since retaining Premier League status on the final day last season, while Raphinha's departure follows the sale of Kalvin Phillips to Manchester City for £45m.