Kris Doolan put Thistle in front, bundling home from close range at the second attempt with 15 minutes left.
Joe Dodoo scores a brace in Rangers comeback win
The 21-year-old came off the bench to score a late goal for Rangers.
Dodoo equalised five minutes later, his crisply-struck volley flying past Thorsten Stuckmann in the Thistle goal.
The 21-year-old struck the winner four minutes into stoppage time, coolly slotting home after being played in by Kenny Miller.
Rangers extend their unbeaten league run to seven matches and though they were below their best, they move above Aberdeen into second place.
Mark Warburton's side were pedestrian in the opening period and though they improved after the break, Thistle will feel they did enough to earn a point.
The harsh reality is that they failed to do so and remain without a home win since the opening day of the season.
Although Thistle play some impressive football, their inability to pick up victories at Firhill could cost them dearly as the season progresses.
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