Rotherham United were relegated to League Two after another home defeat.
In a game of few clear chances, the Millers shaded the first half and Ian Henderson should have done better than head straight at Kieron Westwood.
Rotherham were made to pay when Danny Graham's free kick was blasted into the wall and Kevin Gray forced the ball home from close range on 68 minutes.
The result may have left Rotherham relegated, but it left Carlisle just a point outside the play-off zone.
Rotherham: Cutler, Worrell, Fleming, Mills, Brogan, Henderson (Keane 85), Cochrane (Newsham 63), Jarvis, Woods, O'Grady, Facey.
Subs Not Used: Montgomery, King, Wilson.
Carlisle: Westwood, Raven, Livesey, Murphy (Gray 46), Aranalde, Gall, Joyce (McDermott 84), Lumsdon, Jeff Smith, Garner (Johann Smith 65), Graham.
Subs Not Used: Howarth, Holmes.
Goals: Gray 68.
Rotherham are relegated.
Ref: M Pike (Cumbria).