[4] Hewett made his film debut in the crime drama Pool of London (1951), and later appeared in roles on Robert Montgomery Presents and DuPont Show of the Month.
He appeared as the grandiose and camp theatre director Roger DeBris in Mel Brooks's comedy The Producers (1967).
From 1983 to 1984 he portrayed Lawrence, Mr. Roarke's (Ricardo Montalbán) sidekick on the final season of the ABC series Fantasy Island.
The following year, Hewett landed his best-known role as Lynn Aloysius Belvedere, an English butler who works for a middle class American family in the sitcom Mr.
[5] After the series ended its run in 1990 Hewett appeared in a guest spot on an episode of the NBC teen sitcom California Dreams in 1994.