"She actually called me and she said, 'Hey, you know, I know you're going to be doing the show. Was it OK? Would you be alright if I did it?'" Willis told ET. "And I was like, 'Are you kidding me? Absolutely! I'd love that!' Who gets a free chance to hang out with their mom and work? I'm really excited."
Willis currently stars on the Fox series as former hotshot singer Tory Ash. Meanwhile, Moore -- who appeared in the season three finale -- portrays a mysterious take-charge nurse who will stir things up between Cookie and Lucious. But will mother and daughter be sharing scenes?
"No, we kind of have, we are living in different worlds on the same show, which I think is actually really cool," Willis revealed. "It's fun sometimes because I never necessarily know, other than being at the table read, what the scenes are going to end up being like. So it's fun to kind of watch and get to see. I watched the season finale last year and I was like, 'Oh my gosh, you're so creepy!'"
Willis has been in the industry since she was five -- and has two famous parents in the spotlight. (Her dad is Bruce Willis.) Now that she's crafted a career of her own, what is the best lesson she's learned about being in Hollywood?
"I think the most important thing is just to have, with everything that you do, just show a lot of humility and ... grace," Willis replied. "And make sure that the person that you're presenting to the world is one that you are proud of. And especially for me, you know, being a role model and setting an example, that's important to me."
While fans still have a couple of months until Empire returns, Willis did tease what to expect from her character in the upcoming fourth season.
"I think Tory Ash is just always, kind of, causing trouble and, you know, she's struggling obviously with addiction," she shared. "And I think [she's] trying to figure out who she is and figure out a new form of self-expression, and what that means, and trying to struggle personally as an artist. [And] kind of figuring out her sobriety and figuring out how to fit into a crazy crew."
Empire returns Sept. 27. For more on Willis' role on the drama, watch below.