Tierney was born in Brooklyn, New York, the daughter of Howard Sherwood Tierney and Belle Lavina Taylor. She was named after a beloved uncle, who died young. She had an elder brother, Howard Sherwood “Butch” Tierney, Jr., and a younger sister, Patricia “Pat” Tierney. Their father was a successful insurance broker of Irish descent, their mother a former physical education instructor. Tierney attended St. Margaret’s School in Waterbury, Connecticut, and the Unquowa School in Fairfield. She published her first poem, entitled “Night”, in the school magazine and wrote poetry occasionally throughout her life. Tierney played Jo in a student production of Little Women, based on the novel by Louisa May Alcott.  Tierney spent two years in Europe, attending Brillantmont International School in Lausanne, Switzerland, where she learned to speak fluent French. She returned to the U.S. in 1938 and attended Miss Porter’s School in Connecticut. On a trip to the West Coast, she visited Warner Bros. studios. Director Anatole Litvak, taken by the 17-year-old’s beauty, told her that she should become an actress. Warner Bros. wanted to sign her to a contract, but her parents advised against it because of the relatively low salary; they also wanted her in a higher social position. Tierney’s society debut occurred on September 24, 1938, when she was 17 years old. Soon bored with society life, she decided to pursue an acting career. Her father said, “If Gene is to be an actress, it should be in the legitimate theatre.” Tierney studied acting at a small Greenwich Village acting studio in New York with Broadway director and actor Benno Schneider. She became a protégée of Broadway producer-director George Abbott.

In Tierney’s first role on Broadway, she carried a bucket of water across the stage in What a Life! (1938). A Variety magazine critic declared, “Miss Tierney is certainly the most beautiful water carrier I’ve ever seen!” She also worked as an understudy in The Primrose Path (1938).  The following year, she appeared in the role of Molly O’Day in the Broadway production Mrs. O’Brien Entertains (1939).[4][page needed] The New York Times critic Brooks Atkinson wrote, “As an Irish maiden fresh from the old country, Gene Tierney in her first stage performance is very pretty and refreshingly modest.” That same year, Tierney appeared as Peggy Carr in Ring Two (1939) to favorable reviews. Theater critic Richard Watts, Jr. of the New York Herald Tribune wrote, “I see no reason why Miss Tierney should not have an interesting theatrical career – that is, if cinema does not kidnap her away.” Tierney’s father set up a corporation, Belle-Tier, to fund and promote her acting career. Columbia Pictures signed her to a six-month contract in 1939. She met Howard Hughes, who tried unsuccessfully to seduce her. From a well-to-do family herself, she was not impressed by his wealth. Hughes eventually became a lifelong friend. After a cameraman advised Tierney to lose a little weight, she wrote Harper’s Bazaar magazine for a diet, which she followed for the next 25 years. Tierney was initially offered the lead role in National Velvet, but production was delayed. When Columbia Pictures failed to find Tierney a project, she returned to Broadway and starred as Patricia Stanley to critical and commercial success in The Male Animal (1940). In The New York Times, Brooks Atkinson wrote, “Tierney blazes with animation in the best performance she has yet given”. She was the toast of Broadway before her 20th birthday. The Male Animal was a hit, and Tierney was featured in Life magazine. She was also photographed by Harper’s Bazaar, Vogue, and Collier’s Weekly. Two weeks after The Male Animal opened, Darryl F. Zanuck, the head of 20th Century Fox, was rumored to have been in the audience. During the performance, he told an assistant to note Tierney’s name. Later that night, Zanuck dropped by the Stork Club, where he saw a young lady on the dance floor. He told his assistant, “Forget the girl from the play. See if you can sign that one.” It was Tierney. At first, Zanuck did not think she was the actress he had seen. Tierney was quoted (after the fact), saying: “I always had several different ‘looks’, a quality that proved useful in my career.”

Tierney signed with 20th Century-Fox and her motion picture debut was in a supporting role as Eleanor Stone in Fritz Lang’s western The Return of Frank James (1940), opposite Henry Fonda.  A small role as Barbara Hall followed in Hudson’s Bay (1941) with Paul Muni. In what was a major year of work, Tierney co-starred as Ellie Mae Lester in John Ford’s comedy Tobacco Road, and played the title role in Belle Starr, Zia in Sundown, and Victoria Charteris (Poppy Smith) in The Shanghai Gesture. In 1942, she played Eve in Son of Fury: The Story of Benjamin Blake, as well as the dual role of Susan Miller (Linda Worthington) in Rouben Mamoulian’s screwball comedy film Rings on Her Fingers, and roles as Kay Saunders in Thunder Birds, and Miss Young in China Girl. Receiving top billing in Ernst Lubitsch’s classic 1943 comedy Heaven Can Wait, as Martha Strable Van Cleve, signaled an upward turn in Tierney’s career, and her popularity increased.  In 1944, Tierney starred in what became her most famous role: the title role in Otto Preminger’s film noir Laura, opposite Dana Andrews. After playing Tina Tomasino in A Bell for Adano (1945), she played the jealous, narcissistic femme fatale Ellen Berent Harland, opposite Cornel Wilde, in the film version of the best-selling novel, Leave Her to Heaven by Ben Ames Williams. Her performance won her an Academy Award nomination for Best Actress (1945). This was 20th Century-Fox’ most successful film of the 1940s. It was cited by acclaimed director Martin Scorsese as one of his favorite films of all time, and he assessed Tierney as one of the most underrated actresses of the Golden Era.  In 1946, Tierney starred as Miranda Wells in Dragonwyck, Joseph L. Mankiewicz’ debut film as a director, along with Walter Huston and Vincent Price. That same year, she starred as Isabel Bradley, opposite Tyrone Power, in The Razor’s Edge, an adaptation of W. Somerset Maugham’s novel of the same name. Her performance was critically praised.  Tierney played Lucy Muir in Mankiewicz’s The Ghost and Mrs. Muir (1947), opposite Rex Harrison. The following year, she co-starred again with Power, this time as Sara Farley in the successful screwball comedy That Wonderful Urge (1948). As the decade came to a close, Tierney reunited with Laura director Preminger to star as Ann Sutton in the classic film noir Whirlpool (1949), co-starring Richard Conte and José Ferrer. She gave memorable performances in two other films noirs (both in 1950) – Jules Dassin’s Night and the City and Otto Preminger’s Where the Sidewalk Ends.

In 1951, Tierney was loaned to Paramount Pictures, where she gave a memorable comic turn as Maggie Carleton in Mitchell Leisen’s classic ensemble farce, The Mating Season, with John Lund, Thelma Ritter, and Miriam Hopkins. That same year, she gave a tender performance as Midge Sheridan in the Warner Bros. film, Close to My Heart (1951), with Ray Milland. The film is about a couple trying to adopt a child. Later in her career, she was reunited with Milland in Daughter of the Mind (1969). After Tierney appeared opposite Rory Calhoun as Teresa in Way of a Gaucho (1952), her contract at 20th Century-Fox expired. That same year, she starred as Dorothy Bradford in Plymouth Adventure, opposite Spencer Tracy at MGM. She and Tracy had a brief affair during this time. Tierney played Marya Lamarkina opposite Clark Gable in Never Let Me Go (1953), filmed in England.  Tierney remained in Europe to play Kay Barlow in United Artists’ Personal Affair (1953). While in Europe, she began a romance with Prince Aly Khan, but their marriage plans met with fierce opposition from his father Aga Khan III. Early in 1953, Tierney returned to the U.S. to co-star in film noir Black Widow (1954) as Iris Denver, with Ginger Rogers and Van Heflin.

Tierney had reportedly started smoking after a screening of her first movie to lower her voice, because she felt, “I sound like an angry Minnie Mouse.” She subsequently became a heavy smoker.  With difficult events in her personal life, Tierney struggled for years with episodes of manic depression. In 1943, she gave birth to a daughter Daria who was deaf and mentally disabled, the result of a fan breaking out of rubella quarantine and infecting the pregnant Tierney while she volunteered at the Hollywood Canteen. In 1953, she suffered problems with concentration, which affected her film appearances. She dropped out of Mogambo and was replaced by Grace Kelly. While playing Anne Scott in The Left Hand of God (1955), opposite Humphrey Bogart, Tierney became ill. Bogart had personal experience as he was close to a sister who suffered from mental illness, so during the production, he fed Tierney her lines and encouraged her to seek help. Tierney consulted a psychiatrist and was admitted to Harkness Pavilion in New York. Later, she went to The Institute of Living in Hartford, Connecticut. After some 27 shock treatments, intended to alleviate severe depression, Tierney fled the facility, but was caught and returned. She later became an outspoken opponent of shock treatment therapy, claiming it had destroyed significant portions of her memory. In late December 1957, Tierney, from her mother’s apartment in Manhattan, stepped onto a ledge 14 stories above ground and remained for about 20 minutes in what was considered a suicide attempt. Police were called, and afterwards Tierney’s family arranged for her to be admitted to the Menninger Clinic in Topeka, Kansas. The following year, after treatment for depression, she was released. Afterwards, she worked as a sales girl in a local dress shop with hopes of integrating back into society, but she was recognized by a customer, resulting in sensational newspaper headlines. Later in 1958, 20th Century-Fox offered Tierney a lead role in Holiday for Lovers (1959), but the stress upon her proved too great, so only days into production, she dropped out of the film and returned to Menninger for a time.

Tierney made a screen comeback in Advise and Consent (1962), co-starring with Franchot Tone. A year later, she played Albertine Prine in Toys in the Attic, based on the play by Lillian Hellman. This was followed by the international production of Las cuatro noches de la luna llena, (Four Nights of the Full Moon – 1963), in which she starred with Dan Dailey. She received critical praise overall for her performances.  Tierney’s career as a solid character actress seemed to be back on track as she played Jane Barton in The Pleasure Seekers (1964), but then she suddenly retired. She returned to star in the television movie Daughter of the Mind (1969) with Don Murray and Ray Milland. Her final performance was in the TV miniseries Scruples (1980).  Tierney married two men, the first was Oleg Cassini, a costume and fashion designer, on June 1, 1941, with whom she eloped. Her parents opposed the marriage, as he was from a Russian-Italian family and born in Europe. She and Cassini had two daughters, Antoinette Daria Cassini (October 15, 1943 – September 11, 2010) and Christina “Tina” Cassini (November 19, 1948 – March 31, 2015), born after their first divorce, paternity of whom was the subject of intrigue and speculation at the time due to Tierney’s links with Howard Hughes, Tyrone Power, John Fitzgerald Kennedy and Charles Feldman.  In June 1943, while pregnant with Daria, Tierney contracted rubella (German measles), likely from a fan ill with the disease. Daria was born prematurely in Washington, D.C., weighing three pounds, two ounces (1.42 kg) and requiring a total blood transfusion. The rubella caused congenital damage: Daria was deaf, partially blind with cataracts, and severely mentally disabled. She was institutionalized for much of her life. This was partial inspiration for the Agatha Christie novel The Mirror Crack’d from Side to Side.  Tierney’s friend Howard Hughes paid for Daria’s medical expenses, ensuring the girl received the best care. Tierney never forgot his acts of kindness.

Tierney and Cassini separated October 20, 1946 and entered into a property settlement agreement November 10, 1946. Periodicals during this period record Tierney with Charles Feldman, including articles related to her “twosoming” with Feldman, her “current best beau”. An uncontested divorce followed in California; their final divorce decree was dated March 13, 1948. The couple reconciled on August 19, 1948.  During their separation, Tierney met John F. Kennedy, a young veteran from WWII, who was visiting the set of Dragonwyck in 1946. They began a romance that she ended the following year after Kennedy told her he could never marry her because of his political ambitions. In 1960, Tierney sent Kennedy a note of congratulations on his victory in the presidential election. During this time period, newspapers documented Tierney’s other romantic ensnarements including Kirk Douglas   Tierney remarried Cassini, but they divorced again on February 28, 1952. “Cassini promised in his 1952 divorce from Gene Tierney that he would write a will leaving both of his daughters half of his fortune”. Cassini later bequeathed $500,000 in trust to Daria and $1,000,000 to Christina. Cassini and Tierney remained friends until her death in November 1991.  In 1958, Tierney met Texas oil baron W. Howard Lee, who had been married to actress Hedy Lamarr since 1953. Lee and Lamarr divorced in 1960 after a long battle over alimony, then Lee and Tierney married in Aspen, Colorado on July 11, 1960. They lived quietly in Houston, Texas and Florida until his death in 1981.  In 1960, 20th Century Fox announced Tierney would play the lead role in Return to Peyton Place, but she dropped out of the project after becoming pregnant. She later miscarried.

Tierney died of emphysema in 1991 in Houston. She is interred in Glenwood Cemetery in Houston. Tierney was survived by her daughters Daria and Christina. Daria, born with severe physical and mental disabilities incurred prenatally from her mother’s bout with rubella, died on September 11, 2010, aged 66. Tina died on March 31, 2015 of ovarian cancer in Paris, France. Certain documents of Tierney’s film-related material, personal papers, letters, etc., are held in the Wesleyan University Cinema Archives, to which scholars, media experts, and the public may have access.