Bardot was born a brunette in Paris, the daughter of Louis Bardot (1896–1975) and Anne-Marie "Toty" Bardot (née Mucel; 1912–1978). Louis had an engineering degree and worked with his father, Charles Bardot, in the family Business. Louis and Anne-Marie married in 1933. Bardot grew up in an upper middle-class Roman Catholic observant home. When she was seven she was admitted to the Cours Hattemer, a private school. She went to school three days a week, and otherwise studied at home. This gave time for lessons at Madame Bourget's dance studio three days a week. Brigitte's mother also enrolled Brigitte's younger sister, Marie-Jeanne (born 5 May 1938), in dance. Marie-Jeanne eventually gave up dancing lessons and did not tell her mother, whereas Brigitte concentrated on ballet. In 1947, Bardot was accepted to the Conservatoire de Paris. For three years she attended ballet classes by Russian Choreographer Boris Knyazev. One of her classmates was Leslie Caron. The other ballerinas nicknamed Bardot "Bichette" ("Little Doe").

During her early career, professional Photographer Sam Lévin's photos contributed to the image of Bardot's sensuality. One showed Bardot from behind, dressed in a white corset. British Photographer Cornel Lucas made images of Bardot in the 1950s and 1960s that have become representative of her public persona.

In fashion, the Bardot neckline (a wide open neck that exposes both shoulders) is named after her. Bardot popularized this style which is especially used for knitted sweaters or jumpers although it is also used for other tops and dresses. Bardot popularized the bikini in her early films such as Manina (1952) (released in France as Manina, la fille sans voiles). The following year she was also photographed in a bikini on every beach in the south of France during the Cannes Film Festival. She gained additional attention when she filmed ...And God Created Woman (1956) with Jean-Louis Trintignant (released in France as Et Dieu Créa La Femme). Bardot portrayed an immoral teenager cavorting in a bikini who seduces men in a respectable small-town setting. The film was an international success. The bikini was in the 1950s relatively well accepted in France but was still considered risqué in the United States. As late as 1959, Anne Cole, one of the United States' largest swimsuit designers, said, "It's nothing more than a G-string. It's at the razor's edge of decency." She also brought into fashion the choucroute ("Sauerkraut") hairstyle (a sort of beehive hair style) and gingham clothes after wearing a checkered pink dress, designed by Jacques Esterel, at her wedding to Charrier. She was the subject for an Andy Warhol painting.

Bardot had a small role in a Hollywood-financed film being shot in Paris, Act of Love (1953), starring Kirk Douglas. She received media attention when she attended the Cannes Film Festival in April 1953.

Bardot had a leading role in an Italian melodrama, Concert of Intrigue (1954) and in a French adventure film, Caroline and the Rebels (1954). She had a good part as a flirtatious student in School for Love (1955), opposite Jean Marais for Director Marc Allegret.

She had a small role in The Grand Maneuver (1955) for Director Rene Clair, supporting Gerard Philippe and Michelle Morgan. The part was bigger in The Light Across the Street (1956) for Director Georges Lacombe. She did another with Hollywood film, Helen of Troy, playing Helen's handmaiden.

Finally there was the melodrama And God Created Woman (1956), Vadim's debut as Director, with Bardot starring opposite Jean-Louis Trintignant and Curt Jurgens. The film, about an immoral teenager in a respectable small-town setting, was a huge success, not just in France but also around the world - it was among the ten most popular films in Britain in 1957. It turned Bardot into an international star. In 1958 the moniker "sex kitten" was invented for her.

Bardot followed And God Created Woman with La Parisienne (1957), a comedy co-starring Charles Boyer for Director Boisrond. She was reunited with Vadim in another melodrama The Night Heaven Fell (1958) and played a Criminal who seduced Jean Gabin in In Case of Adversity (1958). The latter was the 13th most seen movie of the year in France.

In May 1958, Bardot withdrew to the seclusion of Southern France, where she had bought the house La Madrague in Saint-Tropez.

In early 1958, after her divorce from Vadim, it was followed in quick order by her break-up with Trintignant and Bardot suffered a reported nervous breakdown in Italy, according to newspaper reports. A suicide attempt with sleeping pills two days earlier was also noted, but was denied by her public relations manager. She recovered within weeks and then began an affair with the actor Jacques Charrier. She became pregnant well before they were married on 18 June 1959. Bardot's only child, her son Nicolas-Jacques Charrier, was born on 11 January 1960. After she and Charrier divorced in 1962, Nicolas was raised in the Charrier family and had little contact with his biological mother until his adulthood.

Bardot released several albums and singles during the 1960s and 1970s

She made a comedy with Vadim, Please, Not Now! (1961) and had a role in the all-star anthology, Famous Love Affairs (1962).

Bardot was awarded a David di Donatello Award for Best Foreign Actress for her role in A Very Private Affair (Vie privée, 1962), directed by Louis Malle. More popular in France was Love on a Pillow (1962), another for Vadim.

In addition to popularizing the bikini swimming suit, Bardot has been credited with popularizing the city of St. Tropez and the town of Armação dos Búzios in Brazil, which she visited in 1964 with her boyfriend at the time, Brazilian musician Bob Zagury. The place where she stayed in Búzios is today a small hotel, Pousada do Sol, and also a French restaurant, Cigalon. The town hosts a Bardot statue by Christina Motta.

More successful was the Western buddy comedy Viva Maria! (1965) for Director Louis Malle, appearing opposite Jeanne Moreau. It was a big hit in France and around the world although it did not break through in the US as much as was hoped.

Bardot's third marriage was to German millionaire playboy Gunter Sachs, and it lasted from 14 July 1966 to 1 October 1969. In 1968, she began dating Patrick Gilles, who went on to costar with her in The Bear and the Doll (1970); but she ended their relationship in the spring of 1971.

Les Femmes (1969) was a flop, although the screwball comedy The Bear and the Doll (1970) performed slightly better. Her last few films were mostly comedies: Les Novices (1970), Boulevard du Rhum (1971) (with Lino Ventura). The Legend of Frenchie King (1971) was more popular, helped by Bardot co-starring with Claudia Cardinale. She made one more with Vadim, Don Juan, or If Don Juan Were a Woman (1973), playing the title role. Vadim said the film marked "Underneath what people call "the Bardot myth" was something interesting, even though she was never considered the most professional Actress in the world. For years, since she has been growing older, and the Bardot myth has become just a souvenir... I was curious in her as a woman and I had to get to the end of something with her, to get out of her and express many things I felt were in her. Brigitte always gave the impression of sexual freedom - she is a completely open and free person, without any aggression. So I gave her the part of a man - that amused me.

In 1973, before her 39th birthday, Bardot announced her retirement. After appearing in more than forty motion pictures and recording several music albums, most notably with Serge Gainsbourg, she used her fame to promote animal rights.

Over the next few years, Bardot dated in succession the bartender/ski instructor Christian Kalt; club owner Luigi Rizzi; musician (later producer) Bob Zagury; singer Serge Gainsbourg; Writer John Gilmore; actor Warren Beatty, and Laurent Vergez, who was her co-star in Don Juan, or If Don Juan Were a Woman. The longest of these Casual relationships was with Sculptor Miroslav Brozek. She lived with him from 1975 to December 1979, posed for some of his sculptures. After breaking up with Brozek, she was involved in a long-term relationship with French TV Producer Allain Bougrain-duBourg.

In 1974, Bardot appeared in a nude photo shoot in Playboy magazine, which celebrated her 40th birthday. On 28 September 1983, her 49th birthday, Bardot took an overdose of sleeping pills or tranquilizers with red wine. She had to be rushed to hospital, where her life was saved after a stomach pump was used to evacuate the pills from her body. Bardot is also a breast cancer survivor.

In 1986, she established the Brigitte Bardot Foundation for the Welfare and Protection of Animals. She became a vegetarian and raised three million francs to fund the foundation by auctioning off jewellery and personal belongings.

She once had a neighbour's donkey castrated while looking after it, on the grounds of its "sexual harassment" of her own donkey and mare, for which she was taken to court by the donkey's owner in 1989. Bardot wrote a 1999 letter to Chinese President Jiang Zemin, published in French magazine VSD, in which she accused the Chinese of "torturing bears and killing the world's last tigers and rhinos to make aphrodisiacs".

Bardot's fourth and current husband is Bernard d'Ormale, a former adviser of Jean-Marie Le Pen, former leader of the far right party Front National; they were married on 16 August 1992.

In her 1999 book Le Carré de Pluton ("Pluto's Square"), Bardot criticizes the procedure used in the ritual slaughter of sheep during the Muslim festival of Eid al-Adha. Additionally, in a section in the book entitled, "Open Letter to My Lost France", Bardot writes that "my country, France, my homeland, my land is again invaded by an overpopulation of foreigners, especially Muslims". For this comment, a French court fined her 30,000 francs in June 2000. She had been fined in 1997 for the original publication of this open letter in Le Figaro and again in 1998 for making similar remarks.

In her 2003 book, Un cri dans le silence ("A Scream in the Silence"), she warned of an "Islamicization of France", and said of Muslim immigration:

On 10 June 2004, Bardot was convicted for a fourth time by a French court for inciting racial hatred and fined €5,000. Bardot denied the racial hatred charge and apologized in court, saying: "I never knowingly wanted to hurt anybody. It is not in my character."

During the 2008 United States presidential election, she branded the Republican Party vice-presidential candidate Sarah Palin as "stupid" and a "disgrace to women". She criticized the former governor of Alaska for her stance on global warming and gun control. She was also offended by Palin's support for Arctic oil exploration and for her lack of consideration in protecting polar bears.

Bardot was idolized by the young John Lennon and Paul McCartney. They made plans to shoot a film featuring The Beatles and Bardot, similar to A Hard Day's Night, but the plans were never fulfilled. Lennon's first wife Cynthia Powell lightened her hair color to more closely resemble Bardot, while George Harrison made comparisons between Bardot and his first wife Pattie Boyd, as Cynthia wrote later in A Twist of Lennon. Lennon and Bardot met in person once, in 1968 at the Mayfair Hotel, introduced by Beatles press agent Derek Taylor; a nervous Lennon took LSD before arriving, and neither star impressed the other. (Lennon recalled in a memoir, "I was on acid, and she was on her way out.") According to the liner notes of his first (self-titled) album, musician Bob Dylan dedicated the first song he ever wrote to Bardot. He also mentioned her by name in "I Shall Be Free", which appeared on his second album, The Freewheelin' Bob Dylan. The first-ever official exhibition spotlighting Bardot's influence and legacy opened in Boulogne-Billancourt on 29 September 2009 – a day after her 75th birthday. The Australian pop group Bardot was named after her.

On 13 August 2010, Bardot lashed out at Director Kyle Newman regarding his plan to make a biographical film on her life. She told him, "Wait until I'm dead before you make a movie about my life!" otherwise "sparks will fly".

On 22 April 2011, French culture minister Frédéric Mitterrand officially included bullfighting in the country's cultural heritage. Bardot wrote him a highly critical letter of protest.

From 2013 onwards the Brigitte Bardot Foundation in collaboration with Kagyupa International Monlam Trust of India has operated annual Veterinary Care Camp. She has committed to the cause of animal welfare in Bodhgaya year after year.

In the book, she contrasted her close gay friends with today's homosexuals, who "jiggle their bottoms, put their little fingers in the air and with their little castrato voices moan about what those ghastly heteros put them through" and that some contemporary homosexuals behave like "fairground freaks". In her own defence, Bardot wrote in a letter to a French gay magazine: "Apart from my husband — who maybe will cross over one day as well — I am entirely surrounded by homos. For years, they have been my support, my friends, my adopted children, my confidants."

On 23 July 2015, Brigitte Bardot condemned Greg Hunt's plan to eradicate 2 million cats to save endangered species such as Warru and Night Parrot.