GaGa took to Twitter in October to ask her 31 million followers to tune into Chicago Fire's premiere.
Chicago Fire star Kinney has now told Extra that GaGa's support has been incredibly meaningful.
"It's great [and] exciting she digs the show. She has been on set," Kinney revealed.
The actor added: "It's great to have someone in your corner, someone that believes in you and is excited about the project you're doing."
Kinney also recently disclosed that he and GaGa have both been very "happy" since they began dating in September 2011.
"I'm in a relationship, and I'm happy. Everything is great," he commented in October.
Chicago Fire airs Wednesdays at 10/9c on NBC.