San Juan died late Saturday at Providence St. Joseph Medical Center in Burbank of kidney failure stemming from a long-term illness, said her son-in-law Barry Adelman, executive producer of the Golden Globe Awards.
San Juan was born March 16, 1927, and raised in Brooklyn, N.Y. She and her family lived in Santurce, Puerto Rico, for three years before returning to New York.
She started dancing at age 5 or 6, Adelman said, and performed as a girl with mambo percussionist Tito Puente. She began her acting career in radio and theater, then went on to movies in the mid-1940s.
"Those were the days where the studios were very active in building images. She was very tiny, but very spunky and lively. So the name 'Puerto Rican Pepperpot' fit," Adelman said.
San Juan appeared opposite Astaire and danced with him in the 1946 musical "Blue Skies" and also sang with Crosby in the film, according to a news release.
She also appeared in such '40s films as "Duffy's Tavern," "Variety Girl" and "One Touch of Venus."
In 1951, she starred in the Broadway production of Lerner and Loewe's "Paint Your Wagon."
San Juan was married for many years to actor Edmond O'Brien. They met at a publicity luncheon for Fox studios and married in 1948, according to the news release. The couple had three children. It was the second marriage for O'Brien, who won a best supporting actor Oscar in 1954 for "The Barefoot Contessa."
San Juan retired in the 1950s to raise her children. The couple divorced in 1976. O'Brien died in 1985.
San Juan is survived by her children, Bridget O'Brien Adelman, a television producer, and actors Maria O'Brien and Brendan O'Brien, as well as her sister Aura Grady and three grandchildren.
A funeral is scheduled for 9 a.m. today at the San Fernando Mission Cemetery in Mission Hills.