The South American, full name Marcio Geovanni Deiberson, completes a permanent move to the Lisbon club following a successful loan spell during the latter half of last season with Jose Antonio Camacho's side.
The 23-year-old has signed a four-year deal at the Estadio de Luz, as the move brings to an end a frustrating two-year spell for the Brazilian at Camp Nou.
Geovanni joined the Catalan club for £14 million from Brazilian outfit Cruzeiro in the summer of 2001 but failed to live up to the hefty price Barca splashed out on the attacking midfield man.
The player's agent Roberto Assuncao successfully negotiated an agreement with Barca vice-president Sandro Rosell that sees Geovanni become a Benfica player for the new season.
The Camp Nou club will have been happy to part with the Brazilian, as Barca look to get their finances under control.
Camacho will be pleased to land Geovanni in time for Benfica's Champions League qualifier against Italian giants Lazio later this month.
