Danny Graham's 71st-minute goal sank Nottingham Forest and moved Carlisle into second place in League One.
Graham grabbed the only goal at the City Ground
Forest had plenty of early chances and Junior Agogo and Julian Bennett were both denied by Carlisle keeper Keiran Westwood, while Kris Commons shot wide.
Carlisle defended in numbers after the break but Graham was in the right place to fire them ahead after Forest goalkeeper Paul Smith fumbled a cross.
Grant Holt fired narrowly wide for Forest but Carlisle held on to triumph.
Nottm Forest: Smith, Perch (McCleary 87), Morgan, Wilson, Bennett, McGugan (Davies 74), Clingan, Cohen, Commons, Agogo, Holt.
Subs Not Used: Richardson, Lockwood, Thornhill.
Carlisle: Westwood, Raven, Murphy, Livesey, Horwood, Taylor, Lumsdon, Grant Smith (Jeff Smith 74), Bridge-Wilkinson, Hackney (Carlton 83), Graham (Madine 90).
Subs Not Used: Howarth, Arnison.
Goals: Graham 71.
Ref: Martin Atkinson (W Yorkshire).