One of four children, Blackman was born in London's East End, to Edith Eliza (Stokes), a homemaker, and Frederick Thomas Blackman, a statistician employed with the Civil Service. She received elocution lessons for her 16th birthday (at her own request), and later attended the Guildhall School of Music and Drama, which she paid for by working as a clerical assistant in the Civil Service. She was also a dispatch rider for the Home Office during World War II, playing an important role in the war effort.

Blackman received her first acting work on stage in London's West End as an understudy in "The Guinea Pig". She continued with roles in "The Gleam" (1946) and "The Blind Goddess" (1947), before moving into film. She debuted with Fame Is the Spur (1947), starring Michael Redgrave.

Blackman suffered a nervous breakdown following her divorce from Bill Sankey, a man 12 years her senior, who's jealousy, fraudulent business practices, and emptying of her bank accounts took it's toll. After hospitalisation Blackman began counselling, which would last for years, and began rebuilding her career.

TV series work also came her way again, most notably the highly popular The Avengers (1961), co-starring Patrick Macnee as John Steed. As the leather-clad "Catherine Gale", Blackman showcased her incredible beauty, self-confidence, and athletic abilities. Her admirable qualities made her not only a catch for the men, but also an inspirational figure for the 1960s feminist movement.

Blackman took on the role of Greek goddess Hera in popular movie adventure Jason and the Argonauts (1963) with Ray Harryhausen and melodrama Life at the Top (1965) with Laurence Harvey. She then played "Pussy Galore" in the classic James Bond film Goldfinger (1964). Blackman went toe to toe with Sean Connery's womanizing "007" and created major sparks on screen.

Blackman continued to work consistently in films and tv, while also appearing on stage where she earned rave reviews as the blind heroine of the thriller "Wait Until Dark" as well as for her dual roles in "Mr. and Mrs.", a production based on two of Noël Coward's plays. She also enjoyed working with her second husband, actor Maurice Kaufmann, in the play "Move Over, Mrs. Markham" and the film thriller Fright (1971). She proved a sultry-voiced sensation in various musicals productions such as "A Little Night Music", "The Sound of Music", "On Your Toes", and "Nunsense."

In the new millennium, Honor was seen in such films as Bridget Jones's Diary (2001), Color Me Kubrick (2005), Reuniting the Rubins (2010), I, Anna (2012) and Cockneys vs Zombies (2012), as well as the British TV serieses Water, Water, Everywhere (1920) The Royal (2003) Coronation Street (1960), long running series Casualty (1986) and finally You, Me & Them (2013), her last role after her retirement several years earlier.

Divorced from Kaufmann in 1975 (although they remained friends until his death, Blackman even cared for him during his 13 year battle with cancer), Blackman never remarried, revealing in an interview that she simply preferred single life, "Basically I'm a shy person and I like my own company". Unable to conceive, the couple adopted two children, Lottie and Barnaby, in '67 and '68 respectively.

The ever-lovely and eternally glamorous star continued to find regular work into her 90s, including co-starring in the long-running English hit comedy series The Upper Hand (1990) and performing her one-woman stage show, "Wayward Women"

Honor Blackman died on April 5, 2020, in Lewes, Sussex. She was 94.