Dawn Addams was born in Felixstowe, East Suffolk, England, the daughter of Captain James Ramage Addams, an R.A.F. officer. Much of her childhood was spent in Calcutta, India, where her father was stationed, and she later attended schools in England and California. Though Dawn took her first screen test at the age of thirteen, she did not start acting until after her graduation from the Royal Academy of Dramatic Art in London. Her career commenced on the repertory stage, with tours of both Britain and continental Europe. Signed to a contract by MGM in 1950, Dawn appeared in her first feature film, Night Into Morning (1951). She acted in several other well-received A-grade productions, including Plymouth Adventure (1952), Young Bess (1953) and The Robe (1953). For Otto Preminger's vaguely controversial The Moon Is Blue (1953), Dawn's services were rented out by MGM to United Artists. In January 1953, she joined other MGM contract stars on a USO tour of Korea. In Charles Chaplin's A King in New York (1957) she had another starring opportunity as an advertising woman who gets involved with royalty. That seemed to mirror her personal life, since Dawn became an actress-princess (prior to Grace Kelly getting that gig) by marrying the Italian nobleman Don Vittorio Massimo in 1954. The marriage ended after just four years in separation and was finally dissolved in 1971.

By the early 1960s, offers of glamorous roles had diminished, and Dawn was down to playing hapless heroines in European co-productions, second string horrors like The Two Faces of Dr. Jekyll (1960) (as Jekyll's wife Kitty who ends up being raped and driven to suicide by his evil alter-ego, Mr. Hyde) and potboilers like Fritz Lang's final directorial effort Die 1000 Augen des Dr. Mabuse (1960). She spent the remainder of her career alternating between stage and television work in England, eventually remarrying and settling down in Malta. In April 1985, Dawn was treated for cancer in Florida but died soon after at a London hospital at the age of 54.