Julien was born in the East End of London, one of the five children of his parents, who had migrated to Britain from St Lucia. He graduated from Saint Martin's School of Art in 1985, where he studied painting and fine art film. He co-founded Sankofa Film and Video Collective in 1983, and was a founding member of Normal Films in 1991.
In 1980, Julien organized the Sankofa Film and Video Collective with Martina Attille, Maureen Blackwood, Nadine Marsh-Edwards, and Robert Crusz in response to the social unrest in Britain. Sankofa was "dedicated to developing an independent black film culture in the areas of production, exhibition and audience". He received a BA in fine-art film from Central Saint Martins School of Art, London (1984), and completed his postdoctoral studies at Les entrepreneurs de l'audiovisuel européen, Brussels (1989). He was also a founding member of Normal Films in 1991.
Julien came to prominence in the film world with his 1989 drama-documentary Looking for Langston, gaining a cult following with this poetic exploration Langston Hughes and the Harlem Renaissance. This following was expanded when his film Young Soul Rebels won the Semaine de la Critique prize for best film at the Cannes Film Festival in 1991.
One of the objectives of Julien's work is to break down the barriers that exist between different artistic disciplines, drawing from and commenting on film, dance, photography, music, theatre, painting and sculpture, and uniting these to construct a powerfully visual narrative. Thematically, much of his work directly relates to experiences of black and gay identity (he is himself gay), including issues of class, sexuality, and artistic and cultural history. He was nominated for the Turner Prize in 2001, and in 2003 he won the Grand Jury Prize at the Kunstfilm Biennale in Cologne for his single screen version of Baltimore. Julien is also a documentary filmmaker - his work in this genre includes BaadAsssss Cinema, a film on the history and influence of blaxploitation cinema.
Julien was appointed Commander of the Order of the British Empire (CBE) in the 2017 Birthday Honours for services to the arts.
Julien readily cites cultural theorist and sociologist Stuart Hall as an important influence on his filmmaking. Hall narrates a portion of "Looking for Langston." Julien involves Hall in his work once more in the 1996 film Frantz Fanon: Black Skin, White Mask which tells the story of Frantz Fanon, the theorist and psychiatrist from Martinique.
Julien is currently living and working in London, England. He was a visiting lecturer at Harvard University's Schools of Afro-American and Visual Environmental Studies, and is currently a visiting professor at the Whitney Museum of American Arts in New York, New York. He was also a research fellow at Goldsmiths College, University of London, and in September 2009 he became a professor at the Karlsruhe University of Arts and Design. Julien is a patron of the Live Art Development Agency.
'Young Soul Rebels', Semaine de la Critique Prize at the Cannes Film Festival (1991).
'Looking For Langston', Teddy Award for Best Short Film at the Berlin International Film Festival (1989).