The home side had by far the best of the first half and Darren Randolph pulled off a wonderful save to deny Gary Teale after a period of sustained pressure.
However, third-placed Motherwell found their stride after the break and St Mirren goalkeeper Craig Samson produced a stunning stop from Michael Higdon to prevent the visitors from leaving with three points.
St Mirren manager Danny Lennon made two changes to his side following the 1-1 William Hill Scottish Cup draw with Ross County last weekend, with Graham Carey and Dougie Imrie returning and David van Zanten and Aaron Mooy dropping to the bench.
Motherwell manager Stuart McCall decided to stick with the side that put six past Morton without reply last weekend, meaning captain Stephen Craigan was on the bench after returning from suspension.
The home side were chasing a first win since Christmas Eve - when they beat Rangers 2-1 - and they made a lively start against a Motherwell side looking for a third successive league victory.
A flowing first-minute move ended with Paul McGowan's shot being blocked by Motherwell defender Tim Clancy. The loose ball fell to Dougie Imrie and his powerful drive was batted away by Motherwell goalkeeper Randolph at his near post.
The visitors took time to settle but home goalkeeper Samson was called into action when he punched Tom Hateley's free-kick to safety in the 10th minute.
Both sides have won plaudits for their attacking play this season but there was a real battle going on in midfield.
Chances were scarce but Imrie combined with Teale to create an opening for Steven Thompson, whose shot was blocked by Clancy.
Graham Carey then burst forward from deep as Motherwell were cut open again - but he dragged his shot wide from 18 yards.
Teale was impressing for St Mirren on the right wing and he almost fired his side ahead on the half hour mark.
Teasing and tormenting Steven Hammell, he cut inside and his deflected shot nearly looped in - with Randolph pulling off a fine stop.
Motherwell were under real pressure and McGowan found a yard of space at the edge of the box and cracked a 20-yard effort inches past the upright.
The visitors had offered little in attack but had a strong penalty claim turned down in the 37th minute when Marc McAusland appeared to foul Nicky Law. Referee Craig Charleston waved away the appeals.
Tempers were frayed and Imrie earned a booking for a challenge on Shaun Hutchinson before the break, much to the disgust of the home fans.
Motherwell began the second half with more purpose and Hutchinson headed over from Hammell's corner seconds after the restart.
That was a let-off for Saints, who then had goalkeeper Samson to thank for keeping the score level in the 50th minute. Higdon met Henrik Ojamaa's cross with a bullet header, but Samson produced a wonderful point-blank stop.
Motherwell were a team transformed after their lacklustre first-half display and continued to press, with Tom Hateley curling a free-kick narrowly wide.
Tackles were flying in as the game threatened to boil over. Hateley was in the thick of a few incidents and was rightly booked for a foul on Carey midway through the half.
Motherwell continued to look the more likely and Shaun Hutchinson glanced a header wide in the 84th minute after meeting Tom Hateley's corner.
St Mirren could not get up the park and Craig Samson was again called into action when he pulled off a fine fingertip save from Ojamaa's curling effort in the closing stages.
There was one final chance for St Mirren when Gary Teale found Paul McGowan at the edge of the box, but he fluffed his shot.
Incredibly, Motherwell then raced up the park in injury-time and almost won it when Chris Humphrey's attempted cross crashed off the bar with Samson beaten.