S. I. Martin was born in Bedford and has worked as a journalist for The Voice and Bulletin. He is the author of a novel, Incomparable World (1996), which tells the story of three black exiles living in 18th-century London; and a non-fiction title, Britain's Slave Trade (1999), published to accompany a television series screened on Channel 4.

S. I. Martin lives in South London where he works as a researcher and writer of Black history. In 2007 his children's novel, Jupiter Williams, was published. It tells the tale of a boy who lives in the African Academy in Clapham, London, in 1800.