Northampton moved seven points clear of the League One drop zone and left Bournemouth deep in trouble after two late goals earned them victory.
Jordan Robertson gave the Cobblers an early lead, scoring at the near post after a cross from Sam Aiston.
The Cherries levelled after the break when Marc Wilson slammed in after Jason Crowe blocked a Warren Cummings shot.
But Kenny Deuchar headed in Andy Holt's cross and Andy Kirk slotted in from close range to wrap up the points.
Northampton: Bunn, Hughes, Pearce, Doig, Crowe, Aiston (Gilligan 64), Taylor, Bradley Johnson, Holt, Robertson (Kirk 73), Deuchar.
Subs Not Used: Jess, Hunt, Dunn.
Goals: Robertson 17, Deuchar 77, Kirk 85.
Bournemouth: Moss, Young, Gowling, Broadhurst, Cooper (Walker 46), Hollands, Purches (Fletcher 46), Wilson, Cummings, Hayter, McGoldrick (Standing 71).
Subs Not Used: Stewart, Pitman.
Goals: Wilson 55.
Ref: P Miller (Bedfordshire).