In theater, Chaplin won the Tony Award for Best Featured Actor in a Musical for his 1957 performance in Bells Are Ringing.

Sydney and his older brother were brought up mostly by their maternal grandmother, while his mother attempted to advance her career as a singer.

[2] After serving in the United States Army during World War II in Europe, Chaplin returned to California, where he became involved in acting both on stage and in films.

[3] He also appeared in several Broadway productions, including Bells Are Ringing opposite Judy Holliday in 1957, for which he won a Tony Award for Best Performance by a Featured Actor in a Musical.

In 1959, he costarred with Lauren Bacall in George Axelrod's comedy Goodbye Charlie and headlined Jule Styne's 1961 musical Subways Are for Sleeping.

Exceptions included his attendance at Cinecon in Los Angeles in 1998, and at the Cineteca di Bologna 2002 festival (Il Cinema Ritrovato), which mounted a fiftieth-anniversary screening of Limelight.