After appearing in the Mad Max and Lethal Weapon series, Gibson went on to direct and star in the Academy Award-winning Braveheart. In 2004, he directed and produced The Passion of the Christ, a controversial, yet successful, film portraying the last hours in the life of Jesus Christ. Outside his career, remarks by Gibson have generated accusations of homophobia, misogyny, and anti-semitism; he has previously attributed the statements to his battle with alcoholism.

Gibson was born in Peekskill, New York, the sixth of 11 children, and the second son of Hutton Gibson and Irish-born Anne Patricia (née Reilly, died 1990). His paternal grandmother was the Australian opera soprano, Eva Mylott (1875–1920). One of Gibson's younger brothers, Donal, is also an actor. Gibson's first name comes from Saint Mel, fifth-century Irish saint, and founder of Gibson's mother's native diocese, Ardagh, while his second name, Colm-Cille, is shared by an Irish saint and is the name of the parish in County Longford where Gibson's mother was born and raised. Because of his mother, Gibson holds dual Irish and American citizenship.

Soon after being awarded $145,000 in a work-related-injury lawsuit against New York Central Railroad on February 14, 1968, Hutton Gibson relocated his family to West Pymble, Sydney, Australia. Gibson was 12 years old at the time. The move to Hutton's mother's native Australia was for economic reasons, and because Hutton thought the Australian military would reject his oldest son for the Vietnam War draft.

Gibson was educated by members of the Congregation of Christian Brothers at St. Leo's Catholic College in Wahroonga, New South Wales, during his high school years.

Gibson gained very favorable notices from film critics when he first entered the cinematic scene, as well as comparisons to several classic movie stars. In 1982, Vincent Canby wrote that “Mr. Gibson recalls the young Steve McQueen... I can't define "star quality," but whatever it is, Mr. Gibson has it.” Gibson has also been likened to “a combination Clark Gable and Humphrey Bogart.” Gibson's roles in the "Mad Max" series of films, Peter Weir's Gallipoli, and the "Lethal Weapon" series of films earned him the label of "action hero". Later, Gibson expanded into a variety of acting projects including human dramas such as Hamlet, and comedic roles such as those in Maverick and What Women Want. He expanded beyond acting into directing and producing, with: The Man Without a Face, in 1993; Braveheart, in 1995; The Passion of the Christ, in 2004; and Apocalypto, in 2006. Jess Cagle of Time has compared Gibson to Cary Grant, Sean Connery, and Robert Redford. Connery once suggested Gibson should play the next James Bond to Connery's M. Gibson turned down the role, reportedly because he feared being typecast.

Gibson studied at the National Institute of Dramatic Art (NIDA) in Sydney. The students at NIDA were classically trained in the British-theater tradition rather than in preparation for screen acting. As students, Gibson and actress Judy Davis played the leads in Romeo and Juliet, and Gibson played the role of Queen Titania in an experimental production of A Midsummer Night's Dream. After graduation in 1977, Gibson immediately began work on the filming of Mad Max, but continued to work as a stage actor, and joined the State Theatre Company of South Australia in Adelaide. Gibson’s theatrical credits include the character Estragon (opposite Geoffrey Rush) in Waiting for Godot, and the role of Biff Loman in a 1982 production of Death of a Salesman in Sydney. Gibson’s most recent theatrical performance, opposite Sissy Spacek, was the 1993 production of Love Letters by A. R. Gurney, in Telluride, Colorado.

While a student at NIDA, Gibson made his film debut in the 1977 film Summer City, for which he was paid $400.

Gibson then played the title character in the film Mad Max (1979). He was paid $15000 for this role. Shortly after making the film he did a season with the South Australian Theatre Company. During this period he shared a $30 a week apartment in Adelaide with his future wife Robyn. After Mad Max Gibson also played a mentally slow youth in the film Tim.

During this period Gibson also appeared in Australian television series guest roles. He appeared in serial The Sullivans as naval lieutenant Ray Henderson, in police procedural Cop Shop, and in the pilot episode of prison serial Punishment which was produced in 1980, screened 1981.

Gibson joined the cast of the World War II action film Attack Force Z, which was not released until 1982 when Gibson had become a bigger star. Director Peter Weir cast Gibson as one of the leads in the critically acclaimed World War I drama Gallipoli, which earned Gibson another Best Actor Award from the Australian Film Institute. The film Gallipoli also helped to earn Gibson the reputation of a serious, versatile actor and gained him the Hollywood agent Ed Limato. The sequel Mad Max 2 was his first hit in America (released as The Road Warrior). In 1982 Gibson again attracted critical acclaim in Peter Weir’s romantic thriller The Year of Living Dangerously. Following a year hiatus from film acting after the birth of his twin sons, Gibson took on the role of Fletcher Christian in The Bounty in 1984. Playing Max Rockatansky for the third time in Mad Max Beyond Thunderdome, in 1985, earned Gibson his first million dollar salary.