Heigl and her husband Josh Kelley adopted a baby girl from Korea in September.
She told People: "I think I'm just gonna try and keep it a little more mellow, and be a little bit more of a mum, since that's a big part of my life now."
Heigl, who failed to return to the Grey's Anatomy set after taking maternity leave, explained that the time she had spent with her family had made her rethink her priorities.
"I took those three months off and realised how very, very important my family is to me and I want to be more available to them," she said. "[My family] is wonderful. They're the icing on the cake."
Heigl is thought to be negotiating an exit from Grey's Anatomy.