Alan Archibald's side could have potentially finished the night in 11th spot, sending them into the last game of the season on Saturday against Ross County as favourites for the relegation play-off spot.
And things got off to a poor start at Tynecastle for the Jags with Callum Paterson putting the hosts ahead after just 16 minutes.
Lyle Taylor soon levelled to give the Glasgow club hope, however the game was only a stalemate for 10 minutes with former Rangers defender Danny Wilson popping up to send the Jambos in to half-time with a 2-1 lead.
However, a barn-storming second half produced three Thistle goals from Gary Fraser, Lee Mair and Kallum Higginbotham to give Archibald's side three invaluable points.
It takes them up to 38 points in the table, with Kilmarnock's win over St Mirren leaving Hibernian rooted to 11th place.
Going into the weekend's fixtures with both Hibs and Killie - who are below Thistle - playing each other, it means the Firhill club will stave off any threat of relegation to remain in the Scottish top flight for two consecutive seasons.