McWilliams's television appearances spanned every decade from the 1960s through the 2000s. She was a regular player on Guiding Light as Janet Mason Norris from 1969 until 1975. She played a prostitute who helped an immigrant stay in the country on Barney Miller in 1977. She was a semi-regular on Soap during the second season in 1978. She then appeared on Benson (as a different character) when that series premiered in 1979. She remained on Benson until 1981: the storyline stated that her character was departing to get married (her fiancé on the show having been played by Ted Danson).
Although she was born in Seattle, McWilliams grew up in Rhode Island. She graduated in 1966 with a bachelor's degree from Carnegie Mellon University in Pittsburgh. She was married in 1982 to Michael Keaton, with whom she had a son, Sean, born in 1983. They divorced in 1990.
Caroline McWilliams died from multiple myeloma at her home in Los Angeles, California on February 11, 2010, aged 64.
