Born in London, England, Ireland was the daughter of a wine importer. She began acting in the mid-1950s with bit parts in films including Simon and Laura (1955) and Three Men in a Boat (1956).

In 1957, Ireland married actor David McCallum. The couple starred opposite each other in The Man From U.N.C.L.E. episode "The Quadripartite Affair" (season 1, episode 3 - 1964) and again four weeks later in episode 7, "The Giuoco Piano Affair". She came back a third time in "The Tigers Are Coming Affair" (episode 37 in 1965) and a fourth in the two-part episode The Five Daughters Affair (season 3, episodes 28 and 29 - 1967). They had three sons, Paul, Valentine, and their adopted son, Jason McCallum, who died of a drug overdose in 1989, six months before Ireland's own death. McCallum and Ireland divorced in 1967.

In 1968, Ireland married Charles Bronson. She had first met him when he and McCallum were filming The Great Escape some years earlier. Together they had a daughter, Zuleika, and adopted a daughter, Katrina. They remained married until Ireland's death in 1990.

Ireland was diagnosed with breast cancer in 1984. After her diagnosis, Ireland wrote two books chronicling her battle with the disease (at the time of her death, she was writing a third book) and became a spokesperson for the American Cancer Society. In 1988, she testified before Congress about medical costs and was awarded the Medal of Courage from then-President Ronald Reagan.

On May 18, 1990, Ireland died of breast cancer at her home in Malibu, California. She was cremated and Bronson had her ashes inserted into a cane which he carried with him the rest of his life. It was later buried with him.

For her contribution to the motion picture industry, Jill Ireland has a star on the Hollywood Walk of Fame at 6751 Hollywood Boulevard.

In 1991, Jill Clayburgh portrayed Ireland in the made-for-television movie Reason for Living: The Jill Ireland Story, which told of her later years, including her fight with cancer.