The 25-year-old has joined the Sky Bet League One side until the end of the season, having trained with Aberdeen and former club Dundee United after being freed by Watford in May. "I do feel I've loads to prove but I have so much hunger," he said.
"I just want to do what I do best on the pitch and start smiling again. This has been a tough year but I'm determined to have a better year ahead. That has started for me with Carlisle giving me a chance."