Rumer Willis is a triple threat ... model, actress AND singer!

Last night, Demi Moore and Bruce Willis' daughter hit the stage at Hollywood's The Sayers Club to sing four songs, and her stepdad Ashton Kutcher was in the crowd cheering her on.

The 23-year-old actress performed the following songs: "(Sittin' On) The Dock of the Bay", "I Can't Stand the Rain", "High Low Middle" and "Age."

Although Demi's ex kept a low profile during the performance, those inside the club say the Two and a Half Men actor took pics with his cell phone.

Too bad Rumer's mom couldn't be there. Then again, wonder if that would be awkward?

See the two leaving the club in our gallery below.