The former Grey's Anatomy and current Private Practice star and her 35-year-old Fox production executive boyfriend, Alex Young, announced last week that they are engaged.
The 39-year-old redhead revealed the surprising news during the ABC upfront presentation at New York's Lincoln Center last Tuesday.
"It happened a few days ago. And that's all I can say," said Kate Walsh, beaming and flashing her Neil Lane engagement ring. "I'm on cloud nine."
The news didn't exactly come as a shock to at least one of her castmates.
"I'm upset because she didn't consult me first!" Walsh's new co-star, Tim Daly, told Us Weekly jokingly.
Walsh and Alex Young only recently went public with their whirlwind romance at a fundraiser for Barack Obama in Los Angeles. Earlier this year, Walsh said she was involved with a special man, but wouldn't reveal his name.
ABC announced earlier this month that Walsh's new show, Private Practice (the Grey's Anatomy spin-off starring her character, Addison Montgomery), had been picked up for a full season and will air on Wednesdays at 9 p.m. in the fall.