Seemingly cruising after leading through goals from Carl Finnigan and Tom Scobbie, a red card for defender Gerard Aafjes turned the game.
Motherwell pulled a goal back from a David Clarkson penalty and then it was backs-to-the-wall stuff from Falkirk.
It should have been much easier. Scott Arfield (twice) and Mark Stewart were clean through on goalkeeper Graeme Smith in the second half but failed to score. Referee Willie Collum's final whistle was the sweetest sound for Falkirk fans.
Falkirk took the lead after nine minutes with a well-worked goal. Arfield played the ball in to Neil McCann in the box and he turned before laying the ball square for Finnigan who had a tap-in from six yards.
But Falkirk almost gifted Motherwell a way back into the game. Jackie McNamara headed on a header from Clarkson towards Dani Mallo and the goalkeeper had to react swiftly to keep it out.
Motherwell came more into things as the half wore on. With Stephen Hughes pulling the strings with some terrific running off the ball, they won a succession of corners.
A wonderful run from Clarkson looked set to bring them some reward but Aafjes made a last-ditch tackle to keep him out.
John Sutton managed to get his head to a Marc Fitzpatrick cross but his looping header in front of Mallo was always too high.
It took a timely intervention from McLean to prevent a clever pass from McCann reaching Stewart just before the interval on a rare Falkirk break.
Falkirk finished the first half strongly. Stewart was denied by Graeme Smith and then Scobbie sent a close-range header wide from McCann's free-kick.
Falkirk started the second half as they had the first, with an early goal to settle them. Incredibly, Scobbie was given another free header from a McCann delivery - this time from a corner - and he was not going to miss twice, leaving Smith with no chance.
Clarkson almost pulled a goal back but Darren Barr was across quickly to divert his shot past the post.
Falkirk should have settled the points moments later when Arfield was clean through but elected to square the ball to Finnigan, over-hit his pass and the chance was lost.
Motherwell found a way back into the game when they were awarded a penalty after 69 minutes. Aafjes was adjudged to have denied Clarkson a goalscoing opportunity and referee Collum pulled out his red card.
Clarkson dusted himself down to drill the spot-kick behind Mallo to leave Falkirk with a battle on their hands for the final 20 minutes.
Steven Pressley was brought on for McCann to replace Aafjes and Kevin McBride and Patrick Cregg also came on.
Stewart should have eased the strain when he galloped in behind the Motherwell defence but lofted his shot high and wide.
Arfield was clear again but Smith pulled off an instinctive save to keep his team in it but Falkirk held on for a valuable win.