Goals from Billy Bodin, Joe Devera, Luke Rooney and Paul Benson coupled with Dagenham striker Josh Scott's sending off helped Paolo Di Canio's side clinch an 11th win in 12 matches.
Bodin was unlucky not to put Swindon in front after dancing past two Daggers defenders before his left-footed shot rebounded off a post. The striker did not have to wait long to get on the scoresheet, sliding in to turn home Benson's cross on 22 minutes.
Dagenham's evening got worse 11 minutes before half time when Scott was shown a straight red card for a reckless challenge on Oliver Risser.
Devera headed Swindon's second from substitute Rooney's corner in the 59th minute before Rooney himself found the net four minutes later with a fierce right-footed drive.
Former Daggers striker Benson tapped in Rooney's cross on the line 15 minutes from time to cap an easy win.
