Xavi's brave strike in the 80th minute levelled the scores at 2-2 and Lionel Messi cut in from the right flank to bury a shot in the far corner four minutes later.
Barca move on to 47 points from 18 games extending their lead over second place, which is now occupied by improving champions Real Madrid, who beat Real Mallorca 3-0 away.
Messi set up Samuel Eto'o for his 16th goal of the campaign just before the break in a frozen Pamplona, but Osasuna bit back in the second half.
"We were lucky at the end but I think we deserved it," Xavi told Canal Plus television.
Real coach Juande Ramos said the quick first goal had made it easier for his side, but denied they were too dependent on Robben's pace. The Dutchman has been their key figure in the last three games.
"A team doesn't rely on one player. It's his job to attack and he is given the freedom to do so by the work of other players," he said.
"Three defeats in a week has put everyone on edge and put doubts in their minds. It's understandable that the fans are angry but we must remain calm," Aguirre said. Atletico are fifth with 30 points, ahead of Villarreal and Deportivo on goal difference.
