Moreno will receive the award at the 20th annual Screen Actors Guild Awards, to be presented Saturday at the Shrine Exposition Center and airing live on TNT and TBS (8 p.m. EST).
The 82-year-old actress has a movie career that dates back to 1950. Early on in Hollywood, she landed an MGM contract, but didn't register her first career triumph until the film adaptation of the stage musical "The King & I."
"'The King & I' was where I met (director-choreographer) Jerome Robbins, because he came to do all of the staging of the musical numbers and he kind of fell in love with doing movies," Moreno said. "And when 'West Side Story' came along a number of years later, I was the first person he thought of for the part of Anita."
Moreno, who was born in Puerto Rico, won a supporting actress Oscar for her performance as a Hispanic gang leader's girlfriend in the 1961 film. She didn't make another movie for nearly seven years.
"It was heartbreaking," she said. "I had played the definitive Hispanic, and that was that."
She kept working, doing TV and theater, and eventually made her way out of the Hollywood rut by providing the inspiration for one of her most memorable characters: a lousy, loopy lounge singer.
"All dancers do bits," Moreno explained. "And one day I said, 'OK, here's this Puerto Rican girl who cannot sing or dance, auditioning for a bus-and-truck (company) of 'Gypsy.'"
She then broke out in a broad, off-key rendition of "Everything's Coming up Roses."
Playwright Terrence McNally caught Moreno's performance and created the character of Googie Gomez, a gay bathhouse performer. Googie provided the big laughs in the stage farce "The Ritz," and Moreno won a 1975 Tony for the role. She then received BAFTA and Golden Globe nominations for her work in the film adaptation.
She was back, on her own terms, and has worked steadily ever since.
"I'm one of the last few people around who do everything," Moreno said. "We sing, we dance, we act. We do comedy. We do drama. So, that's where I come from."