Gus McPherson's men recorded their second win in a row for the first time this season to spread some Christmas cheer just when it looked like the spectre of relegation could dampen the seasonal celebrations.
Only three matches remain to be played at St Mirren Park before the move down the road to their brand new stadium in January, but the threat of displaying their new stadium in the first division next season was turning into a distinct possibility.
St Mirren started the brighter side and took the lead thanks to some dithering in the Inverness midfield, as a loose pass was intercepted by the rampant Andy Dorman who proceeded to race half the length of the pitch, catching the away defence on their heels, before slotting the ball past an isolated Ryan Esson.
The visitors came close to notching one back just before half-time as Richard Hastings whipped a vicious cross into the box. Adam Rooney raced in to try to prod the ball goalwards but could only force his effort inches wide of the post.
Staying focused seems to be an issue with Craig Brewster's men as Thistle were caught napping at the start of the second half. Jim Hamilton was left in space on the left flank and the veteran fired the ball to the back post for Garry Brady to drill his effort into the net.
Hamilton had a great chance to solidify all three points with 15 minutes remaining as Dennis Wyness got to the byline before pulling the ball back to the former Aberdeen man, but the striker could only blast his effort at the legs of Esson.
Wyness was presented with a great chance to score against his former club after some great work on the flank from Brady, but the striker could not find the target.
Brewster tried to tinker with his tactics, but the manager could not find the right formula on the park and the visitors struggled to get a shot on target in the second half.