Carman made her major television debut in 2000 when she starred as Bridget Salsabill in British drama Bomber, though she had previously featured briefly in an episode of City Central. As an Actress, she has also starred in Doctors, Heartbeat and Holby City. She also played the character of Betty Haigh, the wife of John George Haigh, in the television film A is for Acid.

In 2005 she appeared in what would be a recurring role as Kelly Maguire in Shameless. She became a more prominent character in the 2008 series, and finally a main cast member from 2009 to 2013.

In 2011, she played the character Marie in the film Tyrannosaur, written and directed by Paddy Considine.

She appeared in the second series of the BBC 1 drama Prisoners' Wives, starting 14 March 2013, as Kim Haines, the wife of a man falsely accused of child abuse.

Carman discovered Reiki while filming Shameless, and subsequently trained at the Oldham Reiki Network. In March 2014 she started as a therapist at Buddah Beauty, a holistic therapy salon in Chorlton.

Carman was the lead actor in Dreamers a musical play that ran at the Oldham Coliseum in July 2015.

In October 2017, Carman joined the cast of long-running ITV soap opera, Coronation Street, playing Abi Franklin, the drug-addicted mother of established teenage character, Seb Franklin, played by Harry Visinoni.