Katherine Marie Helmond was born on July 5, 1928, in Galveston, Texas. She was raised by her mother, named Thelma Malone, and her grandmother; they were Irish Catholics. Young Katherine Helmond attended Catholic school, and appeared in numerous school plays and pageants. She took a job at local theatre while still in high school, hammering and sawing the scenery, cleaning the bathrooms and pulling the curtain.

Since her stage debut in 'As You Like It', she worked with New York theatres during the 1950s and 1960s. She operated a summer theatre in the Catskills for three seasons and also taught acting in university theatre programs. Helmond made her TV debut in 1962 and had to wait another 10 years until her breakthrough came in the 1970's. At that time she was busy on TV as well as on stage and earned a Tony nomination for 'The Great God Brown' (1973) on Broadway. Although she attended the rigid Bob Jones University, Helmond departed from her conservative roots and became known for her special gift for delivering lines with sexual innuendo. She honed her acting abilities with Alfred Hitchcock in Family Plot and in numerous TV series, notably in the ABC's cult sitcom Soap, for which she had four Emmy nominations and won the Golden Globe. On the big screen she starred in Brazil as Jonathan Pryce's mother who is addicted to plastic surgery and snooping in her son's messed-up life.

In 1983 she studied at Directing Workshop at the American Film Institute and then directed several episodes of TV-series Who's the Boss?. She also picked up Emmy nominations for her role as Mona Robinson, a liberated grandmother in 'Who's the Boss', and as Lois in 'Everybody Loves Raymond'. Although Helmond has been a bona-fide TV star since the 'Soap', she continued working on stage in the 2000s and was acclaimed for her performances in 'Vagina Monologues'.

Katherine Helmond is currently residing in Los Angeles; she also has homes in New York and in London, England.
Of Irish Catholic extraction on the side of her late mother, Thelma Malone. Was nominated for Broadway's 1973 Tony Award as Best Supporting or Featured Actress (Dramatic) for "The Great God Brown."