From 1951 to 1955 Kelly was married to singer-comedian George DeWitt, using the name Claire DeWitt in Son of Sinbad, after which she was seen publicly with Lance Reventlow, son of wealthy heiress Barbara Hutton, singer Frank Sinatra, hotel heir Conrad "Nicky" Hilton, Jr., and actor Perry Lopez, whom she briefly married in 1960-1961, after which she married wealthy banking heir Robert Alan Kenaston, Jr. (d. 1995), son of Actress Billie Dove, in 1961-1963, followed by wealthy Robert Murphy. She once dismissed Prince Aly Khan as "gauche" and Elvis Presley as "a mere child".

On November 6, 1954, Kelly's 3-year-old son Nicholas Christopher DeWitt died after fighting for three days in an iron lung at Variety Children’s Hospital in Miami, Florida, the victim of a rare anesthetic hazard, which happened after he was bitten on the lip by Duke, a cocker spaniel owned by former featherweight champion Willie Pep, and his heart stopped beating as doctors repaired the damage with 25 Stitches.

Kelly went on to roles in films such as The Badlanders (1958), Party Girl (1958), Ask Any Girl (1959) and A Guide for the Married Man (1967). In The Badlanders, a western remake of the film noir The Asphalt Jungle, she played "the Angela role immortalized by Marilyn Monroe" in the original film. In 1959 she was publicized as "the screen's most exciting discovery since Rita Hayworth". In 1964-65 she appeared in several episodes of the television series Burke's Law.