The actress-and-singer, who has starred in films including The Phantom of the Opera and Mystic River, plays Fiona Gallagher in the US adaptation of the successful UK television series.
Emmy discovered the creature roaming around when she was preparing for shooting and says it now has a familiar name.
“I adopted a cat! She was a stray I found outside my trailer. I named her Fiona after my character,” the 24-year-old told Us Weekly.
Emmy lines up alongside famous names such as William H. Macy and Justin Chatwin on Shameless, which is about an uncouth and rowdy family. As the actress doesn’t have any brothers or sisters in real life, she has revealed she has great fun when everyone gets together to watch sport and eat.
“Yes, we hang out off set. I’m an only child and always wanted a big family. Now I’ve got a huge one!” Emmy explained. “For my Thanksgiving, we gathered at my LA house. I made turkey, they made the sides and pies, and we watched football and yelled at the TV.