The 26-year-old actor and Cyrus, 23, called off their engagement in 2013, but the pair reignited the romance late last year, reported Entertainment Tonight.
"Everyone's happy. I'm happy. Yeah," he said.
When asked about the status of his relationship with Miley, Liam said, "I just find it's easier to not talk about my personal life because usually I say the wrong thing, so it ends up just complicating things more. So, I feel like it's better not to talk about it."