The legendary star got picked for Best Supporting Actress in a Motion Picture at the SAG Awards Sunday ... which clearly took her by surprise, but which she handled with gusto and grace in her acceptance speech, coming straight from the heart and chock-full of emotion.

Check out the moment from start to finish, because it was something else. Jamie plants a kiss on her "Everything Everywhere All at Once" costar, Michelle Yeoh, and trotted onstage to a huge standing O.

Her speech itself was also pretty memorable ... with JLC invoking her parents' immigrant heritage and their rise in the Hollywood ranks as actors themselves -- which eventually led her to say, "I know you look at me and think 'Nepo baby,' and I totally get it!"

But she finished with a heartfelt sentiment, adding ... "But I'm 64 years old and this is just amazing." In other words, she's happy to be working as an actor and loves the job -- regardless of how she got there ... that seems to be her takeaway message here.

Say what you want about advantages, but Jamie is totally deserving in her own right. Yes, she's a Nepo Baby ... and no, we don't care. If it means more Jamie Lee -- so be it!