Farrow was born in Los Angeles, California, the third child and eldest daughter of Australian film director John Farrow (John Villiers Farrow) and Irish actress Maureen O'Sullivan, and one of seven children, with older brothers Michael Damien (1939–1958), Patrick (1942–2009), younger brother John Charles (born 1946); and younger sisters Prudence and actresses Stephanie and Tisa. Her eldest brother, Michael Farrow, died in a plane crash in 1958, at age 19; Patrick, a sculptor, committed suicide in 2009; and John Charles was in 2013 sentenced to 10 years in prison for child molestation. Her father's family was originally from England.
Farrow grew up in Beverly Hills, California, where she occasionally put on performances with "toy daggers and fake blood" for passing celebrity tour buses. Aged two, she made her film debut in a short documentary Unusual Occupations: Film Tot Holiday (1947).
She was raised Roman Catholic, and received her primary and high school education at a Catholic convent by nuns. When she was nine, she contracted polio during an outbreak in Los Angeles reportedly affecting 500 people. She was placed in an isolation ward for three weeks and later said the experience "marked the end of my childhood".
Farrow screen-tested for the role of Liesl von Trapp in The Sound of Music, but did not get the part. The footage has been preserved, and appears on the fortieth Anniversary Edition DVD of The Sound of Music. Farrow began her acting career by appearing in supporting roles in several 1960s films, making her first credited appearance in Guns at Batasi (1964). The same year, she achieved stardom on the popular primetime soap opera Peyton Place as naive, waif-like Allison MacKenzie. Farrow left the series in 1966 at the urging of Frank Sinatra whom she married on July 19, 1966. Before her acting career, Farrow worked as a fashion model for many years.
Farrow's first leading film role was in Rosemary's Baby (1968), which was a critical and commercial success at the time and continues to be widely regarded as a classic of the horror genre. Her performance garnered numerous awards, including the Golden Globe Award for New Star of the Year – Actress, and established her as a leading actress. Film critic and author Stephen Farber described her performance as having an "electrifying impact... one of the rare instances of actor and character achieving a miraculous, almost mythical match" wherein the question: Does the diabolic exist, was answered with a reality that could not be controverted. Film critic Roger Ebert called the film "brilliant", and noted, "A great deal of the credit for this achievement must go to Mia Farrow, as Rosemary".
Following Rosemary's Baby, Farrow was to be cast as Mattie in True Grit and was keen on the role. However, prior to filming she made Secret Ceremony in England with Elizabeth Taylor and Robert Mitchum. While filming, Mitchum told her about True Grit director Henry Hathaway having a reputation for being rude to actresses. Farrow asked producer Hal Wallis to replace Hathaway. Wallis refused and Farrow quit the role which was then given to Kim Darby. Secret Ceremony divided critics, but has gone on to develop a devoted following. Farrow's other late 1960s films include John and Mary, opposite Dustin Hoffman.
In the 1970s, Farrow performed in several classical plays in London including Mary Rose, The Three Sisters, and Ivanov. She became the first American actress to join the Royal Shakespeare Company. During this time she appeared in several films, including the thriller See No Evil (1971), French director Claude Chabrol's Docteur Popaul (1972) and The Great Gatsby (1974), in which Farrow played Daisy Buchanan. She appeared in director Robert Altman's cult classic A Wedding (1978). In 1977, she played the title role in The Haunting of Julia. Farrow appeared in several made-for-television films in the 1970s, most notably portraying the title role in a musical version of Peter Pan (1976). In 1979 she appeared on Broadway opposite Anthony Perkins in the play Romantic Comedy by Bernard Slade.
In the 1980s and early 1990s, Farrow's relationship with director Woody Allen resulted in numerous film collaborations. She appeared in nearly all of Allen's films during this period, including leading roles in Zelig, Broadway Danny Rose, The Purple Rose of Cairo, Hannah and Her Sisters, Radio Days and Alice (1990). Farrow played Alura, mother of Kara (Helen Slater), in Supergirl (1984) and voiced the title role in the animated film The Last Unicorn (1982). She narrated several of the animated Stories to Remember. Allen said that the way she played her character in Broadway Danny Rose was a "very, very brave thing for her to do," as she had to play her role without ever using her eyes.
Citing the need to devote herself to raising her young children, Farrow worked less frequently during the 1990s. Nonetheless, she appeared in leading roles in several films, including the Irish film Widows' Peak (1994), Miami Rhapsody (1995) and Reckless (also 1995). She appeared in several independent features and made-for-television films throughout the late 1990s and early 2000s and wrote an autobiography, What Falls Away, in 1997.
Farrow appeared as Mrs. Baylock, the Satanic nanny, in the remake of The Omen (2006). Although the film itself received a lukewarm critical reception, Farrow's performance was widely praised, with the Associated Press declaring "thank heaven for Mia Farrow" and calling her performance "a rare instance of the new Omen improving on the old one." Filmcritic.com added "it is Farrow who steals the show", and the Seattle Post-Intelligencer described her performance as "a truly delicious comeback role for Rosemary herself, Mia Farrow, who is chillingly believable as a sweet-talking nanny from hell." She worked on several films released in 2007, including the romantic comedy The Ex and the first part of director Luc Besson's trilogy of fantasy films, Arthur and the Invisibles. In 2008, in director Michel Gondry's Be Kind Rewind, she appeared opposite Jack Black, Mos Def and Danny Glover. In 2011, Farrow appeared in the film Dark Horse, directed by Todd Solondz.
In September 2014, Farrow returned to Broadway in the play Love Letters. The play was well received by critics with the New York Times calling Farrow's performance "utterly extraordinary… as the flighty, unstable and writing-averse Melissa Gardner."
Farrow became a UNICEF Goodwill Ambassador in 2000 and is a high-profile advocate for human rights in Africa, particularly for children's rights. She has worked to raise funds and awareness for children in conflict-affected regions and to draw attention to the fight to eradicate polio. Farrow has received several awards for her humanitarian work including the Leon Sullivan International Service award, the Lyndon Baines Johnson Moral Courage Award and the Marion Anderson Award. She has set up a campaigning website, miafarrow.org. In 2008, Time magazine named her one of the most influential people in the world.
In 2007, Farrow co-founded the Olympic Dream for Darfur campaign, which drew attention to China's support for the government of Sudan. The campaign hoped to change China's policy by embarrassing it in the run-up to the 2008 Summer Olympics held in Beijing. In March 2007, China said it would urge Sudan to engage with the international community. The campaign persuaded Steven Spielberg to withdraw as an artistic adviser to the opening ceremony. During the Olympics, Farrow televised via the internet from a Sudanese refugee camp to highlight China's involvement in the region.
Farrow and her son Ronan visited 2006 Berlin to be part of a charity auction of United Buddy Bears, which feature designs by artists representing 142 U.N. member states.
She has traveled to Darfur several times. Her third trip was in 2007, with a film crew engaged in making the documentary Darfur: On Our Watch. Later in 2007, Farrow offered to "trade her freedom" for the freedom of a humanitarian worker for the Sudan Liberation Army who was being treated in a UN hospital while under threat of arrest. She wanted to be taken captive in exchange for his being allowed to leave the country. Farrow is also a board member of the Washington, D.C. based non-profit Darfur Women Action Group (DWAG).
In 2009, Farrow narrated a documentary, As We Forgive, relating the struggle of many of the survivors of the Rwandan Genocide to forgive those who murdered family and friends. To show "solidarity with the people of Darfur" Farrow began a water-only fast on April 27. Farrow's goal was to fast for three weeks, but she called a halt after twelve days on the advice of her doctor.
In August 2010, Farrow testified in the trial against former Liberian President Charles Taylor in the Special Court for Sierra Leone.
Farrow has been an activist against Chevron, accusing the oil company of environmental damage in the South American rainforest.
Farrow helped build The Darfur Archives, which document the cultural traditions of the tribes of Darfur. She has filmed some 40 hours of songs, dances, children's stories, farming methods and accounts of genocide in the region's refugee camps that make up the current archives. Since 2011 the Archives have been housed at the Thomas J. Dodd Research Center at the University of Connecticut.
In February 2015 Farrow appeared in an episode of A Path Appears, a PBS documentary series from the creators of the Half the Sky movement. In the episode Farrow travels to Kibera, Kenya’s largest slum, to share stories from organizations providing education to at-risk girls.
In the 2016 Democratic presidential election, Farrow endorsed democratic socialist Bernie Sanders.
In February 1968, Farrow traveled to India, where she spent part of the year at the ashram of Maharishi Mahesh Yogi in Rishikesh, Uttarakhand, studying Transcendental Meditation. Her visit received worldwide media attention because of the presence of all four members of The Beatles, Donovan, and Mike Love, as well as her sister Prudence Farrow, who inspired John Lennon to write the song "Dear Prudence".
Though she has been critical of the Roman Catholic church (notably in the Pope's failure to intervene in the genocide in Rwanda, a predominately Catholic country), she maintained in a 2013 interview with Piers Morgan that she had not "lost her faith in God." Since the 1990s, Farrow has resided at Frog Hollow farm, a farm in Bridgewater, Connecticut.
On July 19, 1966, Farrow married singer Frank Sinatra at the Las Vegas home of Jack Entratter. Farrow was 21 years old at the time while Sinatra was 51. Sinatra wanted Farrow to give up her acting career which she initially agreed to do. She accompanied Sinatra while he was shooting several films but soon tired of doing nothing and signed on to star in Rosemary's Baby. Filming for Rosemary's Baby ran over its initial estimated filming schedule which angered Sinatra who had cast Farrow in a role in his film The Detective. After Farrow failed to report for filming, Sinatra cast actress Jacqueline Bisset in Farrow's role. In November 1967, while Farrow was filming Rosemary's Baby, Sinatra's lawyer served her with divorce papers. Their divorce was finalized in August 1968. Farrow later blamed the demise of the marriage on their age difference and stated that she was an "impossibly immature teenager" when she married Sinatra. The two remained friends until Sinatra's death.
On September 10, 1970, Farrow married conductor and composer André Previn in London. At the time of their marriage, Farrow was pregnant with twin boys. Farrow had begun a relationship with Previn while he was still married to his second wife songwriter Dory Previn. When Farrow became pregnant, Previn left Dory and filed for divorce. Their divorce became final in July 1970. Dory Previn later wrote a scathing song, entitled "Beware of Young Girls", about the loss of her husband to Farrow. Previn and Farrow divorced in 1979.
In 1979, Farrow began a relationship with film director Woody Allen. During their relationship, Farrow starred in 13 of Allen's films, and several of her relatives also made appearances. Their relationship ended in 1992 when Allen began having an intimate relationship with Soon-Yi, her 21-year-old adopted daughter.
As of September 2016, Farrow has 11 living children (four biological, seven adopted), including her adopted daughter Soon-Yi from whom she is estranged. Three of her adopted children, Tam, Lark, and Thaddeus, are deceased.
Farrow and former husband André Previn have three biological children: twins Matthew and Sascha (born February 26, 1970), and Fletcher (born March 14, 1974), now the CIO of IBM. In 1973 and 1976, respectively, they adopted Vietnamese infants, Lark Song Previn and Summer "Daisy" Song Previn, followed by the adoption of Soon-Yi from Korea around 1978. Soon-Yi's precise age and birth date are not known, but a bone scan estimated her age as being between 5 and 7 years old at the time of her adoption.
In 1985, Farrow adopted Dylan Farrow (born July 1985, adopted at two weeks old). Dylan was known as "Eliza" for a while and also as "Malone". In December 1991 a New York City court allowed Woody Allen to co-adopt Dylan and Moses.
On December 19, 1987, Farrow gave birth to their son Satchel O'Sullivan Farrow, later known as Ronan Farrow. In a 2013 interview with Vanity Fair, Farrow stated Ronan could "possibly" be the biological child of her first husband Frank Sinatra, with whom she claimed to have "never really split up".
On January 13, 1992, Mia Farrow discovered that Woody Allen has been having an affair with her adopted daughter, Soon-Yi, and ended their relationship.
On August 4, 1992, Dylan Farrow, then aged seven, told Farrow that she had been sexually abused by Allen in their Connecticut home earlier that day. Farrow reported this to their pediatrician, who reported the allegations to authorities. Allen was informed of the accusations on August 6. A week later, on August 13, Allen sued for full custody of his biological son, Satchel, and two of Farrow's adopted children, Dylan and Moses, with whom Allen had assumed a parental role.
In March 1993, the lead doctor of Yale–New Haven Hospital Child Sexual Abuse Clinic's investigation into the allegations, Dr. John Leventhal, gave sworn testimony via a deposition that, in his opinion, Dylan "either invented the story under the stress of living in a volatile and unhealthy home or that it was planted in her mind by her mother" because of the "inconsistent" presentation of the story by Dylan. The doctor did not meet with Dylan before giving his testimony and delivered his findings based on interviews conducted by others.
The team's findings were criticized by the presiding judge, and later by other experts in the field, who found their behaviour unusual for making conclusive statements about innocence and guilt, instead of reporting on behaviour, for refusing to testify in court when asked, and for destroying all their notes. Justice Wilk stated that the investigating team's behaviour had "resulted in a report which was sanitized and, therefore, less credible" and that its recommendations and statements had "exceed[ed] its mandate". He concluded, "I am less certain, however, than is the Yale-New Haven team, that the evidence proves conclusively that there was no sexual abuse."
In his final decision, in June 1993, Justice Wilk stated that he found "no credible evidence to support Mr. Allen's contention that Ms. Farrow coached Dylan or that Ms. Farrow acted upon a desire for revenge against him for seducing Soon-Yi. Mr. Allen's resort to the stereotypical 'woman scorned' defense is an injudicious attempt to divert attention from his failure to act as a responsible parent and adult." He rejected Allen's bid for full custody and denied him visitation rights with Dylan, stating that even though the full truth of the allegations may never be known, "the credible testimony of Ms. Farrow, Dr. Coates, Dr. Leventhal and Mr. Allen does, however, prove that Mr. Allen's behavior toward Dylan was grossly inappropriate and that measures must be taken to protect her".
In September 1993, the state's attorney, Frank Maco, announced he would not pursue Allen in court for the molestation allegations, despite having "probable cause", citing his and Farrow's desire not to traumatise Dylan further.
In February 2014, Dylan Farrow publicly renewed her claims of sexual abuse against Allen, in an open letter published by Nicholas Kristof, a friend of Farrow, in his New York Times blog. Allen repeated his denial of the allegations.
Following the new allegations, Moses Farrow claimed Mia had physically abused him. Moses also asserted that Mia Farrow had coached her children into believing stories she made up about Allen.
Between 1992 and 1995, Farrow adopted five more children: Tam Farrow; Kaeli-Shea Farrow, later known as Quincy Maureen Farrow; Frankie-Minh; Isaiah Justus; Gabriel Wilk Farrow, later known as Thaddeus Wilk Farrow and named after Elliott Wilk, the judge who oversaw Farrow's 1993 legal battle with Allen. Tam Farrow died of heart failure in 2000 at the age of 19 after a long illness. On December 25, 2008, Lark Previn died at the age of 35, also after a long illness, and although the cause of death was not disclosed, she had previously been treated for AIDS-related pneumonia. On September 21, 2016, Thaddeus Wilk Farrow was found dead at the age of 27 after an apparent car crash. The Connecticut state medical examiner later ruled the death a suicide after an autopsy revealed that Thaddeus had shot himself in the torso.