After losing their last three matches in their worst ever start to the season, Gibson revved up his troops, who were trailing 25-6 at AAMI Park, and they responded with four second-half tries to snatch the victory.
It was sealed in the 80th minute when the Waratahs took advantage of the Rebels losing Colby Fainga'a to a yellow card and Sefa Naivalu down with a dislocated shoulder.
Centre David Horwitz ran on to a Nick Phipps pass and threw a dummy before scooting through some skinny defence for the match-winner.