Samuel Eto'o broke the deadlock seconds from the interval before Miguel Flano scored an equalizer for the home side on 63 minutes.
Ten minutes later, Walter Pandiani put Osasuna ahead, but Xavi Hernandez and Lionel Messi struck on 80 and 85 respectively to earn their team a deserved win.
Having amassed three points, Barcelona remained 12 points clear of second-placed Real Madrid.
Barca got the upper hand during the first half, but failed to translate their dominance into goals till Cameroonian ace Eto'o hit the opener.
The hosts notably redeemed themselves in the second half and bagged a double.
Flano headed a remarkable leveler before Pandiani diverted Juanfran's cross in Victor Valdes' net.
Barcelona seemed to be on the verge of slumping to a second Liga defeat this season.
However, Josep Guardiola's men retaliated and overturned the one-goal deficit, thanks to Xavi's tame shot and Messi's impressive left-footed drive.