Scott McGleish struck a second-half brace as Northampton held off Carlisle's late rally to claim victory.
Andy Kirk put the Cobblers ahead with a first-time shot from the edge of the box from Bradley Johnson's pass.
McGleish then made it 2-0 with a neat finish from Eoin Jess' volley and he scored again from a rebound after Keiren Westwood had saved from Jess.
Danny Graham pulled one back after Mark Bunn saved from Kevin Gall and Gall then drilled in, but the hosts held on.
Northampton: Bunn, Chambers, Dyche, Brett Johnson, Crowe, Burnell (Bojic 83), Jess, Bradley Johnson, Holt, Kirk, McGleish.
Subs Not Used: Dunn, Aiston, Hunt, Quinn.
Booked: Burnell.
Goals: Kirk 45, McGleish 47, 71.
Carlisle: Westwood, Arnison, Livesey, Gray, Aranalde, Thirlwell, Lumsdon, McDermott (Holmes 70), Hawley, Graham, Gall.
Subs Not Used: Williams, Billy, Joyce, Krause.
Booked: McDermott, Gray, Gall, Aranalde, Holmes.
Goals: Graham 82, Gall 86.
Att: 5,549
Ref: F Graham (Essex).