Credit: Marc Stamas/

She's got a rock from Mr. 30 Rock!

After less than a year of dating, Alec Baldwin is engaged to yoga instructor Hilaria Thomas, says a rep for the 30 Rock star, who turns 54 on Tuesday.

"Yes, it's true!" Baldwin's rep Matthew Hiltzik tells Us Weekly. "Alec proposed to Hilaria this weekend and we're all excited for the newly engaged couple. Alec's birthday is tomorrow. Great way to celebrate!"

The actor (who's been talking up his potential plans to run for mayor of New York City in the near future) first stepped out with the stunning 28-year-old at various high-profile NYC bashes in May 2011.

Following his infamously bitter 2002 divorce from Kim Basinger after nine years of marriage -- he and the actress, 58, battled over custody of their daughter Ireland, now 16, among other things -- Baldwin had been committed to staying single.

But that all changed with Thomas, and Baldwin even sold his Upper West Side apartment to move in downtown with his new love.

Thomas is "very humble, very sweet, very down-to-earth and very charming," Alec's brother Stephen Baldwin told Us in October. "I'm glad that they're into each other. Alec's a lot calmer and a lot happier."