Demi Moore was "so proud" of her daughter's Hollywood concert on Feb 18 (Tues).
The 51-year-old actress -- who was accompanied by her boyfriend Sean Friday -- appeared "mesmerised" by eldest girl Rumer Willis' performance of covers at the Sayers Club earlier this week.
A source told Us Weekly magazine: "Demi and Sean looked really comfortable with one another. It was obvious Demi wasn't there for a night out but was there simply to support her daughter.
"Demi literally couldn't take her eyes off her daughter. She looked mesmerised by Rumer's voice."
"Sean was tapping his knee along to the beat. Demi had a huge grin as she looked at the crowd admiring her daughter. She was so proud."
Rumer -- whose set included covers of Free's 'All Right Now', Miley Cyrus' 'Wrecking Ball', Roberta Flack's 'Killing Me Softly' and Lesley Gore's 'You Don't Own Me' -- was thrilled to have her mother and her musician boyfriend in the audience, heading straight to the table when she finished on stage.
The source continued: "Rumer looked really happy to have their support. You could tell it meant a lot to her that Demi and Sean were there."
As well as Rumer, Demi -- whose divorce from third husband Ashton Kutcher was finalised last November, almost two years after they split -- also has daughters Scout, 22, and Tallulah, 21, with former spouse Bruce Willis.