The We Can't Stop singer looked gorgeous on the arm of her fiancé for the premiere of his new film Paranoia, as the two stepped at the DGA Theatre in Los Angeles on Thursday night.
Wearing a red and black leather Proenza Schouler dress and sky-high white Celine heels, Miley smiled proudly as her Hunger Games actor boyfriend worked the carpet.
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Liam was dapper in a sharp black Boss suit as he promoted his new espionage thriller, in which he stars alongside Harrison Ford and Amber Heard.
When asked what his latest film may do for his acting career the 23-year-old told reporters that he picks every film "for different reasons."
"And every film I grow as an actor and, I think, as a person, especially when you work with these kinds of actors. It was nice to see how much they still cared about film. You know they love makings movies and that's what I love to do."
Since Liam and Miley got together after meeting on the set of their film The Last Song in 2009, they have kept fans guessing as to whether they remain an item.
Recently, Miley, 20, denied rumours of a budding romance with Justin Bieber after the pair were spotted together at a club in Los Angeles.
"I'm engaged! I'm engaged. That is impossible," she said in a morning interview on Washington DC radio programme The Kane Show, at the time.
Australian actor Liam popped the question to the former Hannah Montana star with a 3.5 carat Neil Lane engagement ring in June last year.
Although Miley has since been seen with and without her dazzling diamond ring, she had it firmly on her finger at Thursday's premiere.