Britney Spears & Sam Asghari Make Red Carpet Debut at 'Once Upon a Time in Hollywood' Premiere

Britney Spears made a rare red carpet appearance at the Once Upon a Time in Hollywood premiere!

The 37-year-old entertainer stepped out at the event with boyfriend Sam Asghari on Monday evening (July 22) in Hollywood, Calif.

PHOTOS: Check out the latest pics of Britney Spears

They were also joined at the premiere by Robin Thicke and his fiancee April Love Geary as well as John Stamos and his wife Caitlin McHugh.

Once Upon a Time in Hollywood visits 1969 Los Angeles, where everything is changing, as TV star Rick Dalton and his longtime stunt double Cliff Booth make their way around an industry they hardly recognize anymore.

The film hits theaters on July 26th.

FYI: Britney is wearing a Nookie dress. Guests at the premiere enjoyed specialty Casamigos cocktails and shots in boot shaped shot glasses.