Livingston youngster Kyle Lander marked his debut with a goal as the Lions ran riot at The Rock.
Livi fended off early chances for Jim Lister before Lander grabbed the opener midway through the first half.
Paul Watson doubled Livi's lead through a header before Danny Mullen netted Livi's third.
Alan Lithgow was unlucky not to pull a goal back when he hit the crossbar for the Sons.
But Livingston returned with three three-deserved points in the bag.
Grindlay, Ashgar, Creaney (Horne 66), Graham, Lithgow, Turner, Gilhaney, Agnew, Lister (Metcalfe 78), Lamont, McDougall (Prunty 52)
Subs not used: Ronald, Lumsden
McNeil, McCann (Donaldson 81), Booth (Downie 78), Garcia Tena, Barr, Watson, Ky.Jacobs, O'Brien, Lander (Mullen 72), Fox, Talbot
Subs not used: Gray, Jamieson
Referee: Willie Collum
Official Attendance: 705
Match report: Kieran Westbrook