Northampton continued their 100% winning record against Dagenham with victory in their sixth meeting.
Abu Ogogo diverted Clive Platt's flick-on into his own net to give the Cobblers the lead, before Chris Hackett neatly finished for 2-0.
Kevin Langmead added a third when he headed home Ben Tozer's delivery.
The Daggers did reduce the deficit through Scott Doe, who capitalised on poor defending to drive home, but his side could not find a way back.
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Manager Aidy Boothroyd told BBC Radio Northampton:
"I thought it was scrappy today at best. There's games when you ride your luck and we did that today.
"The scoreline flattered us, but we take it because football's like that.
"We've got the consistency at home and we need to maintain it, and get it away from home now.
"I'll get the Clarke Carlisle deal sorted to get him in our side for Saturday - and we've been really pleased with Lewis Hornby, we've offered him a new contract."