He has put pen to paper with the club on a four and a half year deal, which includes a hefty release clause of €150m.
The signing was not expected to go through until the summer but Barcelona took matters into their own hands and finalised the deal in this window because of the problems he was facing in France.
"We snapped him up when we did because we needed to protect him," Abidal said.
"His situation at Toulouse was becoming untenable and it was important for us to bring him here in order to be able to help him grow and improve as a player.
"He is very versatile and can play in several positions.
"He is excellent in the air, assured in possession and young.
"It is a very exciting signing for the club and he has all of the requisites to become an important player for the club in the future.
"He has only played 10 matches so far, but you only need to watch him play once to see that he oozes ability."