Livingston moved to within one point of Championship leaders Falkirk by inflicting the Bairns' first home league defeat since April 2023.
Robbie Muirhead fired Davie Martindale's Lions ahead from the penalty spot after on-loan Hearts midfielder Macaulay Tait was felled by Falkirk goalkeeper, Nicky Hogarth.
John McGlynn's side - who were last beaten on league duty at the Falkirk Stadium by Edinburgh City when in League 1 - started the brighter and should have been in front through Barney Stewart, on his first start since joining from Heriot Watt University.
They were left to rue that, and a handful of other chances, even more when Reece McAlear got the final touch during a mad melee just before half-time.
The stop-start nature of the night did not suit the usually fluid Falkirk, though they did snatch one back through a penalty of their own.
Stewart delayed his fall after feeling contact from Ryan McGowan, but referee Graham Grainger did not hesitate in pointing to the spot.
Like Muirhead, Brad Spencer coolly slotted into the left corner, but his effort could not energise the league leaders enough to net a second. Keelan Adams came closest to an equaliser with a powerful drive in the dying embers of stoppage time.
Ayr United now have the chance to take over at the top if they can beat Hamilton Academical on Saturday.