Under-pressure Partick produced an outstanding performance to all but seal their play-off place and virtually end Albion's hopes of reaching the top four.
The visitors won at Forthbank for the third time this season and had to do it the hard way after falling behind to a disputed early penalty, but they dominated and thoroughly deserved their success.
The winning goal was long overdue when it finally arrived with 11 minutes left – David Craig heading home a Sean Kilgannon corner as Thistle's pressure paid off.
Albion took the lead after just six minutes when Steven Bell went down under a challenge from Scott McCulloch and referee Andrew Hunter deemed it a penalty, which Chris Aitken confidently converted.
That should have been a platform for the Binos, but instead it was Dick Campbell's men who took charge and Adam Strachan rattled the post before Mark Roberts was denied by the offside flag.
Thistle must have worried it wasn't going to be their day, but those fears were eased 90 seconds after the interval when skipper Marc Smyth's low 20-yard shot sneaked just inside the post.
It was all Partick, and Strachan sent a header inches wide before Mark McNally cleared a Stephen McConalogue effort of the line and Smyth rattled the post from just outside the box.
Craig's header put Thistle in front after 79 minutes and, although Stirling substitute Chris Hay struck the woodwork late on, it would have been a travesty if the Firhill outfit had been denied victory.