Pasolini was born in Bologna, traditionally one of the most leftist politically of Italian cities. He was the son of Carlo Alberto Pasolini, a lieutenant in the Italian army, and Susanna Colussi, an elementary school Teacher. His parents married in 1921, Pasolini was born in 1922 and named after his paternal uncle. His family moved to Conegliano in 1923 and, two years later, to Belluno, where another son, Guidalberto, was born.

In 1926, Pasolini's father was arrested for gambling debts. His mother moved with the children to her family's house in Casarsa della Delizia, in the Friuli region. That same year, his father Carlo Alberto, first detained and then identified Anteo Zamboni as the would-be Assassin of Benito Mussolini following his assassination attempt. Carlo Alberto was persuaded of the virtues of fascism.

Pasolini began writing poems at the age of seven, inspired by the natural beauty of Casarsa. One of his early influences was the work of Arthur Rimbaud. In 1931, his father was transferred to Idria in the Julian March (now Idrija in Slovenia); in 1933 they moved again to Cremona in Lombardy, and later to Scandiano and Reggio Emilia. Pasolini found it difficult to adapt to all these dislocations, though he enlarged his poetry and literature readings (Dostoyevsky, Tolstoy, Shakespeare, Coleridge, Novalis) and left behind the religious fervour of his early years. In the Reggio Emilia high school, he met his first true friend, Luciano Serra. The two met again in Bologna, where Pasolini spent seven years completing high school. Here he cultivated new passions, including football. With other friends, including Ermes Parini, Franco Farolfi, Elio Meli, he formed a group dedicated to literary discussions.

In 1939 Pasolini graduated and entered the Literature College of the University of Bologna, discovering new themes such as philology and aesthetics of figurative arts. He also frequented the local cinema club. Pasolini always showed his friends a virile and strong exterior, totally hiding his interior turmoil. He took part in the Fascist government's culture and Sports competitions. In his poems of this period, Pasolini started to include fragments in Friulan, a dialect, now officially recognised as a minority language he did not speak but learned after he had begun to write poetry in it. "I learnt it as a sort of mystic act of love, a kind of félibrisme, like the Provençal poets."

In 1942, the family took shelter in Casarsa, considered a more tranquil place to wait for the conclusion of the Second World War, a decision Common among Italian military families. In the weeks before the 8 September armistice, Pasolini was drafted. He was captured and imprisoned by the German Wehrmacht, but escaped disguised as a peasant and found his way to Casarsa. Here he joined a group of other young enthusiasts of the Friulan dialect who wanted to give Casarsa Friulan a status equal to that of Udine, the official regional standard. From May 1944 they issued a magazine entitled Stroligùt di cà da l'aga. In the meantime, Casarsa suffered Allied bombardments and forced enlistments by the Italian Social Republic, as well as partisan activity.

On 30 October 1945, Pasolini joined the pro-devolution association Patrie tal Friul, founded in Udine. The political status of the region became a matter of contention between different political factions. Pasolini wanted a Friuli based on its tradition, attached to its Christianity, but intent on civic and social progress, as opposed to those advocates of regional autonomy who wanted to preserve their privileges based on "immobilism". He also criticized the Communist Party for its opposition to devolution and their preference for Italian centralism. He founded the party Movimento Popolare Friulano, but ended up quitting it, persuaded that it had come to be controlled and used by the Christian-Democrat Party in order to counter the Yugoslavians, who in turn were attempting to annex large swaths of the Friuli region.

In 1946 Pasolini published a small poetry collection, I Diarii ("The Diaries"), with the Academiuta. In October he traveled to Rome. The following May he began the so-called Quaderni Rossi, handwritten in old school exercise books with red covers. He completed a drama in Italian, Il Cappellano. His poetry collection, I Pianti ("The cries"), was also published by the Academiuta.

The next month, when questioned, he would not deny the facts, but talked of a "literary and erotic drive" and cited André Gide, the 1947 Nobel Prize for Literature laureate. Cordovado informed his superiors and the regional press stepped in. According to Pasolini, the Christian-Democrats instigated the entire affair to smear his name ("the Christian-Democrats pulled the strings"). He was fired from his job in Valvasone and he was expelled from the Communist Party by the party's Udine section, which he considered a betrayal. He addressed a critical letter to the head of the section, his friend Ferdinando Mautino and claimed he was being subject to a "tacticism" of the Communist Party. In the party, the expulsion was opposed by Teresa Degan, Pasolini's colleague in education. He also wrote her a letter admitting his regret for being "such a naive, even indecently so". His parents reacted angrily and the situation in the family became untenable.

A small scandal broke out during a local festival in Ramuscello in September 1949. Someone informed Cordovado, the local sergeant of the carabinieri, of sexual conduct (masturbation) by Pasolini with three youngsters aged sixteen and younger after dancing and drinking. Cordovado summoned the boys' parents, who hesitated, but did not file charges, despite Cordovado's urging. He nevertheless drew up a report, and the informer elaborated publicly on his accusations, sparking a public uproar. A judge in San Vito al Tagliamento charged Pasolini with "corruption of minors and obscene acts in public places". He and the 16-year-old were both indicted.

In January 1950 Pasolini moved to Rome with his mother Susanna to start a new life. He was acquitted of both charges in 1950 and 1952. "I came to Rome from the Friulan countryside. Unemployed for many years; ignored by everybody; driven by the fear to be not as life needed to be". After one year sheltered in a maternal uncle's flat next to Piazza Mattei, Pasolini and his 59-year-old mother moved to a run-down suburb called Rebibbia, next to a prison, for 3 years; he transferred his Friulan countryside inspiration to this Roman suburb, one of the infamous borgate where poor proletarian immigrants lived in often horrendous sanitary and social conditions. Instead of asking for help from other Writers, Pasolini preferred to go his own way.

He found a job working in the Cinecittà film studios and sold his books in the 'bancarelle' ("sidewalk shops") of Rome. In 1951, with the help of the Abruzzese-language poet Vittorio Clemente, he found a job as a secondary school Teacher in Ciampino, a suburb of the capital. He had a long commute involving two train changes and earned a meagre salary of 27,000 Italian lire.

In 1954, Pasolini, who now worked for the literary section of Italian state radio, left his teaching job and moved to the Monteverde quarter. At this point, his cousin Graziella moved in. They also accommodated Pasolini's ailing, cirrhotic father Carlo Alberto who died in 1958. Pasolini published La meglio gioventù, his first important collection of dialect poems. His first novel, Ragazzi di vita (English: Hustlers), was published in 1955. The work had great success but was poorly received by the PCI establishment and, most importantly, by the Italian government. It initiated a lawsuit for "obscenity" against Pasolini and his Editor, Garzanti. Although exonerated, Pasolini became a target of insinuations, especially in the tabloid press.

Pasolini's first novel, Ragazzi di vita (1955), dealt with the Roman lumpenproletariat. The book caused obscenity charges to be filed against Pasolini, the first of many instances in which his art provoked legal problems. The movie Accattone (1961), also about the Roman underworld, also provoked controversy, and conservatives demanded stricter censorship by the government.

In 1957, together with Sergio Citti, Pasolini collaborated on Federico Fellini's film Le notti di Cabiria, writing dialogue for the Roman dialect parts. He also co-wrote the dialogue for Fellini's La dolce vita.

Pasolini's stance finds its roots in the belief that a Copernican change was taking place in the Italian society and the world. Linked to that very idea, Pasolini was also an ardent critic of consumismo, i.e. consumerism, which he felt had rapidly destroyed Italian society since the mid 1960s to the early 1970s. As he saw it, the society of consumerism ("neocapitalism") and the new fascism had thus expanded an alienation / homogenization and centralization that the former clerical-fascism had not managed to achieve, so bringing about an anthropological change.

During this period Pasolini frequently traveled abroad: in 1961, with Elsa Morante and Alberto Moravia to India (where he went again seven years later); in 1962 to Sudan and Kenya; in 1963, to Ghana, Nigeria, Guinea, Jordan and Israel (where he shot the documentary, Sopralluoghi in Palestina). In 1970 he traveled again to Africa to shoot the documentary, Appunti per un'Orestiade africana.

As a Director, Pasolini created a picaresque neorealism, showing a sad reality. Many people did not want to see such portrayals in artistic work for public distribution. Mamma Roma (1962), featuring Anna Magnani and telling the story of a prostitute and her son, was an affront to the public ideals of morality of those times. His works, with their unequaled poetry applied to cruel realities, showing that such realities were less distant from most daily lives, and contributed to changes in the Italian psyche.

In 1963 Pasolini met "the great love of his life," fifteen-year-old Ninetto Davoli, whom he later cast in his 1966 film Uccellacci e uccellini (literally Bad Birds and Little Birds but translated in English as The Hawks and the Sparrows). Pasolini became the youth's mentor and friend. "Even though their sexual relations lasted only a few years, Ninetto continued to live with Pasolini and was his constant companion, as well as appearing in six more of his films."

He wrote and directed the black-and-white The Gospel According to Matthew (1964). It is based on scripture, but adapted by Pasolini, and he is credited as Writer. Jesus, a barefoot peasant, is played by Enrique Irazoqui. While filming it, Pasolini vowed to direct it from the "believer's point of view", but later said that upon viewing the completed work, he realized he had expressed his own beliefs.

In his 1966 film Uccellacci e uccellini (literally Bad Birds and Little Birds but translated in English as The Hawks and the Sparrows), a picaresque—and at the same time mystic—fable, Pasolini hired the great Italian Comedian Totò to work with Ninetto Davoli, the director's lover at the time and one of his preferred "naif" actors. It was a unique opportunity for Totò to demonstrate that he was a great dramatic actor as well.

In 1967, in Venice, he met and interviewed the American poet Ezra Pound. They discussed the Italian movement neoavanguardia and Pasolini read some verses from the Italian version of Pound's Pisan Cantos.

His films won awards at the Berlin International Film Festival, Cannes Film Festival, Venice Film Festival, Italian National Syndicate for Film Journalists, Jussi Awards, Kinema Junpo Awards, International Catholic Film Office and New York Film Critics Circle. The Gospel According to St. Matthew was nominated for the United Nations Award of the British Academy of Film and Television Arts (BAFTA) in 1968.

In 1970 Pasolini bought an old castle near Viterbo, several miles north of Rome, where he began to write his last novel, Il Petrolio, where he denounced obscure dealing in the highest levels of government and the corporate world (the ENI, CIA, the mafia, etc.). The novel-documentary was left incomplete at his death. In 1972 he started to collaborate with the extreme-left association Lotta Continua, producing a documentary, 12 dicembre, concerning the Piazza Fontana bombing. The following year he began a collaboration for Italy's most renowned newspaper, Il Corriere della Sera.

Later movies centered on sex-laden folklore, such as Boccaccio's Decameron (1971), Chaucer's The Canterbury Tales (1972), and Il fiore delle mille e una notte (literally The Flower of 1001 Nights, released in English as Arabian Nights, 1974). These films are usually grouped as the Trilogy of Life. While basing them on classics, Pasolini wrote the screenplays and took sole credit as Writer. This trilogy, prompted largely by Pasolini's attempt to show the secular sacredness of the body against man-made social controls and especially against the venal hypocrisy of religious state (indeed, the religious characters in The Canterbury Tales are shown as pious but amorally grasping fools) were an effort at representing a state of natural sexual innocence essential to the true nature of free humanity. Alternately playfully bawdy and poetically sensuous, wildly populous, subtly symbolic and visually exquisite, the films were wildly popular in Italy and remain perhaps his most enduringly popular works. Yet despite the fact that the trilogy as a whole is considered by many as a masterpiece, Pasolini later reviled his own creation on account of the many soft-core imitations of these three films in Italy that happened afterwards on account of the very same popularity he wound up deeply uncomfortable with. He believed that a bastardisation of his vision had taken place that amounted to a commoditisation of the body he had tried to deny in his trilogy in the first place. The disconsolation this provided is seen as one of the primary reasons for his final film, Salo, in which humans are not only seen as commodities under authoritarian control but are viewed merely as ciphers for its whims, without the free vitality of the figures in the Trilogy of Life.

His final work, Salò (Salò, or the 120 Days of Sodom, 1975), exceeded what most viewers could accept at the time in its explicit scenes of intensely sadistic violence. Based on the novel 120 Days of Sodom by Marquis de Sade, it is considered Pasolini's most controversial film. In May 2006, Time Out's Film Guide named it the "Most Controversial Film" of all time. Salò was intended as the first film of his Trilogy of Death, followed by an aborted biopic film about Gilles de Rais.

Pasolini's work often engendered disapproval perhaps primarily because of his frequent focus on sexual behavior, and the contrast between what he presented and what was publicly sanctioned. While Pasolini's poetry often dealt with his gay love interests, this was not the only, or even main, theme. His interest in and use of Italian dialects should also be noted. Much of the poetry was about his highly revered mother. He depicted certain corners of the contemporary reality as few other poets could do. His poetry, which took some time before it was translated, was not as well known outside Italy as were his films. A collection in English was published in 1996.

Twenty-nine years later, on 7 May 2005, Pelosi retracted his confession, which he said had been made under the threat of violence to his family. He claimed that three people "with a Southern accent" had committed the murder, insulting Pasolini as a "dirty communist."

In 2014 Abel Ferrara directed a biopic about Pasolini, with Willem Dafoe in the lead role. It was selected to compete for the Golden Lion at the 71st Venice International Film Festival.

In 2015 Malga Kubiak directed a drama movie based on the story of Pier Paolo Pasolini's life and death titled PPPasolini. The movie was screened at the 7th edition of the LGBT Film Festival In Warsaw, Poland and received a People's Choice Award at the festival.