If you're a fan of the show, chances are you've been wondering what happened to jimmy shameless since season 3. The rebellious rich man Steve/Jimmy/Jack first appeared on the series as a grand theft auto "thief" with a whole backstory. He had a wealthy family that didn't know about his lifestyle and even a fake name to go with it. He began wooing the oldest Gallagher daughter Fiona (Emmy Rossum) and they started dating. But he was also a womanizer and a thief and that's what ultimately ended their relationship. At the end of season three, he was supposedly killed by a South American drug lord's daughter whom he was pretending to be married to.
In season 4, he returned, but only to tell Fiona that he was still alive, and she gave him a piece of her mind. In the last episode of season four, he shows up at the Gallagher home with an unidentified woman to invite them to a party. Fiona declines.
The show's executive producer John Wells explained Chatwin's exit saying that he did great work and the character was coming to an end. But he also said there is a possibility that Jimmy could return at some point in the future, but it would be hard for fans to get excited about that since Fiona and Jimmy's storyline seems to have concluded with their fight in the last episode of the season.