Weiss was born in Nowawes (now part of Potsdam-Babelsberg), Brandenburg, to a Hungarian Jewish father and Christian mother. At age three he moved with his family to Bremen, and then during his adolescence to Berlin where Weiss began training for a career as a visual artist. In 1934 he emigrated with his family to Chislehurst, near London, England, where he studied photography at the Polytechnic School of Photography, and then in 1937-1938 attended the Prague Art Academy. After the German occupation of the Sudetenland in 1938, his family moved to Sweden, and Weiss himself removed to Switzerland. In 1939 he again emigrated to Stockholm, Sweden, where he lived for the rest of his life. He became a Swedish citizen in 1946.

Weiss was married three times: to the painter Helga Henschen, 1943; to Carlota Dethorey, 1949; and to Gunilla Palmstierna, 1964. He was politically active as a member of the Communist Party of Sweden, and in 1967 participated in Bertrand Russell's tribunal against the Vietnam War in Stockholm.

In 1970 Weiss suffered a heart attack. During the following decade his writing turned away from plays and focused on his three part novel, The Aesthetics of Resistance. He died in Stockholm in 1982.

Weiss' first art exhibition took place in 1936. His first produced play was Der Turm in 1950. In 1952 he joined the Swedish Experimental Film Studio, where he made films for several years. During this period, he also taught painting at Stockholm's People's University, and illustrated a Swedish edition of The Book of One Thousand and One Nights. Since the early 1950s, Weiss also wrote prose. His work consists of short and intense novels with Kafkaesque details and feelings, often with autobiographical background. Among the short films by Weiss The Studio of Doctor Faust (1956) shows a persisting link of the emigrant Weiss to a German cultural background. One of the better known films made by Peter Weiss is the experimental production The Mirage (1959). In Paris, Weiss directed another film together with Barbro Boman called Play Girls or The Flamboyant Sex (Schwedische Mädchen in Paris or Verlockung in German) in 1960.

Weiss' best-known work is the play Marat/Sade (1963), first performed in West Berlin in 1964, which brought him widespread international attention. The following year, legendary director Peter Brook staged a famous production in New York City. The play examines the power in society through two extremely different historical persons, Jean-Paul Marat, a brutal hero of the French Revolution, and the Marquis de Sade, for whom sadism was named. In Marat/Sade, Weiss uses the technique of presenting a play within a play: "Our play's chief aim has been to take to bits great propositions and their opposites, see how they work, and let them fight it out."

In 1965, Weiss wrote the documentary play The Investigation (Die Ermittlung) on the Frankfurt Auschwitz Trials. A translation of Weiss' The Investigation was performed at London's Young Vic theater by a Rwandan company in November 2007. The production presented a dramatic contrast between the play's view on the Holocaust and the Rwandan actors' own experience with their nation's genocide.

Between 1971 and 1981 Weiss was working on his three part novel on the European resistance against Nazi Germany, The Aesthetics of Resistance.

Weiss was honored with the Charles Veillon Award, 1963; the Lessing Prize, 1965; the Heinrich Mann Prize, 1966; the Carl Albert Anderson Prize, 1967; the Thomas Dehler Prize, 1978; the Cologne Literature Prize, 1981; the Bremen Literature Prize, 1982; the De Nios Prize, 1982; the Swedish Theatre Critics Prize, 1982; and the Georg Büchner Prize, 1982.

All works were originally written in German unless otherwise noted. English translations are in parentheses.

Plays

• 1949 Der Turm (The Tower)
• 1952 Die Versicherung
• 1963 Nacht mit Gästen (Night with Guests)
• 1963/5 Die Verfolgung und Ermordung Jean Paul Marats dargestellt durch die Schauspielgruppe des Hospizes zu Charenton unter Anleitung des Herrn de Sade (The Persecution and Assassination of Jean-Paul Marat as Performed by the Inmates of the Asylum of Charenton under the Direction of the Marquis de Sade) - generally known as Marat/Sade
• 1963/8 Wie dem Herrn Mockinpott das Leiden ausgetrieben wird (How Mr. Mockinpott was cured of his Sufferings)
• 1965 Die Ermittlung (The Investigation)
• 1967 Gesang vom lusitanischen Popanz (Song of the Lusitanien Bogey)
• 1968 Diskurs über die Vorgeschichte und den Verlauf des lang andauernden Befreiungskrieges in Viet Nam als Beispiel für die Notwendigkeit des bewaffneten Kampfes der Unterdrückten gegen ihre Unterdrücker sowie über die Versuche der Vereinigten Staaten von Amerika die Grundlagen der Revolution zu vernichten (Discourse on the Progress of the Prolonged War of Liberation in Viet Nam and the Events Leading up to it as Illustration of the Necessity for Armed Resistance against Oppression and on the Attempts of the United States of America to Destroy the Foundations of Revolution) - generally known as Viet Nam Diskurs
• 1969 Trotzki im Exil (Trotsky in Exile)
• 1971 Hölderlin
• 1974 Der Prozeß - adaptation of Franz Kafka's novel
• 1982 Der neue Prozeß (The New Trial)

Fiction

• 1944 Från ö till ö (From Island to Island; written in Swedish; German: Von Insel zu Insel)
• 1948 De besegrade (The Conquered; written in Swedish; German: Die Besiegten)
• 1948 Der Vogelfreie (published as Dokument I in Swedish (1949) and in German as Der Fremde under the pseudonym Sinclair)
• 1951 Duellen (The Duel; written in Swedish; German: Das Duell)
• 1952 Der Schatten des Körpers des Kutschers (The Shadow of the Coachman's Body)
• 1956 Situationen (The Situation; written in Swedish; German: Die Situation)
• 1960 Abschied von den Eltern (Leavetaking)
• 1961 Fluchtpunkt (Vanishing Point)
• 1962 Das Gespräch der drei Gehenden (The Conversation of the Three Walkers)
• 1975-1981 Die Ästhetik des Widerstands (Published in 3 volumes, I: 1975; II: 1978; III: 1981) (The Aesthetics of Resistance)

Other writings

• 1956 Avantgarde Film (written in Swedish)
• 1968 Rapporte
• 1970 Rekonvaleszenz
• 1971 Rapporte 2
• 1971-1980 Notizbücher

Films

• 1952 Studie I (Uppvaknandet) Sweden, 16mm, 6min)
• 1952 Studie II (Hallucinationer) / Study II (Hallucinations) (Sweden, 16mm, 6min)
• 1953 Studie III / Study III (Sweden, 16mm, 6min)
• 1954 Studie IV (Frigörelse) / Study IV (Liberation), (Sweden, 16mm, 9min)
• 1955 Studie V (Växelspel)/Study V (Interplay),(Sweden, 16mm, 9min)
• 1956 Ateljeinteriör / Dr. Fausts Studierstube(Atelierinterieur) (Sweden, 10 min)
• 1956 Ansikten I Skugga / Faces in the shadow (Sweden, 13 min)
• 1957 Enligt Lag / According To Law (co-dir. Hans Nordenström, Sweden, 16mm, 18 min)
• 1958 Vad ska vi göra nu da? / Was machen wir jetzt? (Sweden, 20min)
• 1959 Hägringen / Fata Morgana (Sweden, 81min) Starring: Staffan Lamm and Gunilla Palmstierna.