Archie Campbell's hat-trick gave Morton their first win of the season as Dumbarton sustained a fourth consecutive defeat.
The Sons tested the home side early on and Morton goalkeeper Derek Gaston had to be alert to tip Scott Agnew's 30-yard effort past the post.
Morton came into the game when Michael Tidser's drilled 25-yard shot cannoned back off the woodwork.
Campbell broke the deadlock two minutes before the break with a left-foot shot into the bottom right-hand corner.
The striker grabbed his second with a well-placed penalty after Andy Graham had fouled David O'Brien.
Allan Moore's men sealed the points when Campbell found the bottom right-hand corner from 12 yards after 76 minutes.
The striker squandered the chance of a fourth goal when his 89th-minute penalty struck the crossbar.
Morton: Gaston, Taggart, Reid, Mark McLaughlin, Dyer, Graham (Wallace 85), Bachirou (Wilkie 80), Tidser, O'Brien, Weatherson (Hawke 82), Campbell. Subs Not Used: Hutton, Naismith.
Goals: Campbell 43, 54 pen, 76.
Dumbarton: Grindlay, Devlin, Lithgow, Andy Graham, Creaney, Fleming (McNiff 55), Gilhaney (Lamont 82), Agnew, McDougall (Johnston 82), Lister, Prunty. Subs Not Used: Ewings, Forsyth.
Booked: Prunty, Creaney, McNiff.
Ref: Bobby Madden