Sorry gals, Twilight's Kellan Lutz is taken

It's official. Twilight hunk Kellan Lutz, who's also starring in the new film Immortals, is officially dating Australian actress Sharni Vinson.

The two stepped out together at the Immortals premiere in Los Angeles earlier this week and Lutz confirmed their relationship status during an appearance on the radio show On Air with Ryan Seacrest Friday morning.

"I'm very happily with someone, yeah," replied Lutz when Vinson's name was spoken. "[Vinson's a] happy person, which really just clicks with me. It's just great to have someone who you smile with all the time. It's very special."

Aww.

Vinson, 28, is perhaps best known for her starring role in Step-Up 3D. Lutz, who plays Emmett Cullen in the Twilight series, dated AnnaLynne McCord of 90210 fame for about two years before breaking up in the fall of 2010.

As for Immortals, the 3D fantasy romp stars Henry Cavill, Freida Pinto and Mickey Rourke. Lutz plays Poseidon, the god of the seas. But Lutz didn't mind getting wet for the role.

"I live in water," said Lutz to Seacrest. "I just grew up always in a pool, I did swimming and lifeguard training growing up. It was just something growing up in the Midwest, North Dakota and Arizona, you're in all these hot-tempered cities, you kind of need a pool… I love swimming -- it's the best cardio and it's great on the joints. I'm just a natural water type of guy."

Lutz has a swimmer's body-plus in Immortals. But he didn't get that cut just by swimming.

"We had an open gym, 24/7 [on the set]," Lutz said. "We didn't have strict gym times." Lutz continued joking about their body-revealing attire, "We were in skirts half the time -- very manly skirts -- so we didn't have to be afraid of getting makeup or anything on the clothing. We could go sweat it out and go do our scene."

Also look for Lutz -- sans manly skirt -- in The Twilight Saga: Breaking Dawn -- Part 1, which opens Nov. 18.

Photo courtesy of WENN