The Sons’ Dimitris Froxylias went close with a fizzing 25-yard effort that just cleared Neil Alexander’s bar on 23 minutes – but that was to be their high point.
Livingston opened the scoring in a scrappy fashion on 31 minutes when Lee Miller forced the ball in from six yards – but their second came five minutes later in a sublime manner as Ryan Hardie chipped Scott Gallacher from 25 yards.
Raffaele De Vita rolled in the third right on half-time after he got the better of Gallacher in an aerial joust.
Livingston had two astonishing misses in quick succession around the hour mark.
Firstly Hardie hit Gallacher’s legs with his team-mates screaming for a pass.
Then, seconds later, Josh Mullin shot against the outside of the post.
Dumbarton’s afternoon got worse when Aidan Wilson picked up his second booking and was dismissed ten minutes from time.