Goals by Danny Jackman, Ade Akinfenwa and Jason Crowe, the first two of them inside a four-minute spell in the first half, consigned injury-hit Yeovil to defeat, which means Russell Slade's men are now without a victory in eight matches.
This was sweet for Northampton as Yeovil were the only side to register a league double against them last season and Jackman set the ball rolling with a 17th minute free-kick which he curled over the wall and in off a post to beat Asmir Begovic.
Almost before the Glovers had a chance to resettle, they found themselves 2-0 behind when Akinfenwa latched on to a pass from Andy Holt before firing a low drive from the edge of the box for his eighth goal of the season.
Yeovil threatened briefly with Paul Warne and Kieran Murtagh both having shots charged down by Frank Fielding, but Abdul Osman was unlucky not to make it 3-0 when his close-range effort was cleared off the line by Murtagh.
The second half started in a livelier fashion with Gavin Tomlin's snapshot bringing a great reaction save by Fielding, while a Karl Hawley header from a Luke Guttridge chip went straight at Begovic.
Yeovil must have known they were out of luck when Tomlin cut into the box in the 56th minute only to see his fierce shot flash past the far post and the Glovers were reduced to ten men with 14 minutes left on the clock, when Terrell Forbes reacted angrily to a challenge from Osman and was shown a straight red card by referee Kevin Wright.
The player advantage helped Town produce some slick football in the closing stages and this was highlighted by a sweet finish from Crowe eight minutes from time when he rounded off a five-man move.