And the Bairns were the architects of their own downfall with some crazy defending, gifting Killie the vital goals.
New signing Dean Holden knocked a short free-kick straight into the path of Steven Naismith, who played a clever ball into Colin Nish allowing the big striker to slide home a low finish.
And five minutes later Kilmarnock increased their lead from a corner. Rocco Quinn sent in the ball from the left and Simon Ford rose unchallenged to power a header off the crossbar.
The Falkirk defence were slow to react and Naismith pounced to fire the ball into the roof of the net.
Falkirk offered little as an attacking force and a super pass from the left by Garry Hay saw Nish only inches away with his first-time effort from 15 yards.
Kilmarnock could have increased their lead after the break had it not been for two fine saves from Kasper Schmeichel.
His first stop kept out Naismith's close-range volley and he then raced off his line to block Nish's low effort with his legs.
Falkirk failed to muster any real challenge and will have to do much better on Tuesday night if they hope to take anything from their CIS Cup semi-final.