Trocchi was born and educated in Glasgow. After working as a seaman on the Murmansk convoys, he attended University of Glasgow. On graduation he obtained a traveling grant which enabled him to relocate to continental Europe. In the early 1950s, he lived in Paris and edited the literary magazine Merlin, which published Henry Miller, Samuel Beckett, Christopher Logue, and Pablo Neruda, amongst others. Although not published in Merlin, American writer Terry Southern, who lived in Paris from 1948?1952, became a close friend of both Trocchi and his colleague Richard Seaver and the three later co-edited the anthology Writers In Revolt (1962). Though established somewhat in rivalry with the Paris Review, George Plimpton also had served on Merlin's editorial board.
Trocchi claimed that this journal came to an end when the U.S. State Department canceled its many subscriptions in protest over an article by Jean-Paul Sartre praising the homoeroticism of Jean Genet.
Maurice Girodias published most of Trocchi's novels through Olympia Press, often written under pen names, such as Frances Lengel and Carmencita de las Lunas.
Girodias also published My Life and Loves: Fifth Volume, which purported to be the final volume of the autobiography of Irish writer Frank Harris. However, though based on autobiographical material by Harris, the book was heavily edited and rewritten by Trocchi.
Trocchi acquired his lifelong heroin addiction in Paris. He left Paris for the United States and spent time in Taos, New Mexico, before settling in New York City, where he worked on a stone scow on the Hudson river. This time is chronicled in the novel Cain's Book, which at the time became something of a sensation, being an honest study of heroin addiction with descriptions of sex and drug use that got it banned in Britain, where the book was the subject of an obscenity trial; in America, however, it received favourable reviews.
Trocchi was then deep in the thralls of heroin addiction; he even failed to attend his own launch party for Cain's Book. His wife Lyn prostituted herself on the streets of the Lower East Side. He shot up on camera during a live television debate on drug abuse, despite being on bail at the time. He had been charged with supplying heroin to a minor, an offence then punishable by death. A jail term seemed certain, but with the help of some friends (including Norman Mailer), Trocchi was smuggled over the Canadian border where he met up with Leonard Cohen. His wife Lyn was arrested and son Marc detained, but later joined Trocchi in London.
In the late 1950s he lived in Venice, then the center of the Southern California Beat scene. In October 1955 he became involved with the Lettrist International and then the Situationist International. His text "Invisible Insurrection of a Million Minds" was published in the Scottish journal New Saltire in 1962 and subsequently as "Technique du Coup du Monde" in Internationale Situationniste, number 8. It proposed an international "spontaneous university" as a cultural force and marked the beginning of his movement towards his sigma project, which played a formative part in the UK Underground. He resigned from the SI in 1964.
Trocchi appeared at the 1962 Edinburgh Writers Festival where he claimed "sodomy" as a basis for his writing. During the festival, Hugh MacDiarmid denounced him as "cosmopolitan scum". However, while this incident is well known, it is little remarked upon that the two men subsequently engaged in correspondence, and actually became friends. Trocchi then moved to London, where he remained for the rest of his life.
He began a new novel, The Long Book, which he did not finish. Much of his sporadic work of the 1960s was collected as The Sigma Portfolio. He continued writing but published little. He opened a small book store near his Kensington home. He was known in Notting Hill as "Scots Alec." He died of pneumonia.
Interest in Trocchi and his role in the avant-garde movements of the mid-20th century began to rise soon after his death. Edinburgh Review published a "Trocchi Number" in 1985 and their parent house published the biography, The Making of the Monster by Andrew Murray Scott, who had known Trocchi for four years in London and who went on to compile the anthology, Invisible Insurrection, in 1991, also for Polygon. These works were influential in bringing Trocchi back to public attention. Scott assisted the Estate in attempting to regain control of Trocchi's material and to licence new editions in the UK and USA and Far East, also collating and annotating all remaining manuscripts and documents in the Estate's possession.
During the 1990s, various American and Scottish publishers (most notably Rebel Inc.) reissued his originally pseudonymous Olympia Press novels and a retrospective of his articles for Merlin and others, A Life in Pieces (1997), was issued in response to revived interest in his life and work by a younger generation. His early novel Young Adam was adapted into a film starring Ewan McGregor and Tilda Swinton in 2003 after several years of wrangling over finance.
Tainted Love (2005) by Stewart Home contains a lengthy 'factional' meditation on Trocchi's post-literary career period in Notting Hill.