The 40-year-old actress and 50-year-old New Jersey senator and presidential hopeful attended the event Thursday at the Regency Village Theatre in Westwood.
Dawson and Booker wore coordinating navy suits to the premiere. The couple were all smiles as they held hands, kissed and snapped selfies on the red carpet.
Booker shared a video on Instagram Stories of himself and Dawson joking in front of of a Big Fat Death monster truck that Dawson got to drive during filming.
"You know, you've been doing these RV tours, right? You're really missing out. It's the monster truck tour," Dawson says.
"We'll go in a monster truck to Iowa," Booker jokingly responds.
Zombieland: Double Tap is a sequel to Zombieland (2009), and co-stars Woody Harrelson, Jesse Eisenberg, Emma Stone and Abigail Breslin. Dawson plays Nevada, a new survivor and Tallahassee's (Harrelson) love interest in the film, which opens in theaters Oct. 18.
Dawson and Booker were first linked in January after attending a Broadway musical. Dawson voiced her love for Booker in an interview with TMZ in March.
"So far, so wonderful," she said of the relationship. "I am just grateful to be with someone that I respect and love and admire so much, who is so brilliant, kind and caring and loving."