Born in Winnipeg, Manitoba, Ian Lancashire went to school at Churchill High School and received his B.A. Honours degree in English and Philosophy from the University of Manitoba in 1964. He received his M.A. (1965) and Ph.D. (1969) at the University of Toronto and became a lecturer in 1968 at Erindale College. He joined the Records of Early English Drama project in 1975 and founded the Centre for Computing in the Humanities in 1985. Stepping down from that directorship, he became founding editor of  Representative Poetry Online in 1994 and editor of Lexicons of Early Modern English in 2006. The University of Toronto Press published his Forgetful Muses in 2010, a study of the neuroscientific basis of literary creativity. He retired in 2012 but maintains a laboratory in the Robarts Library for his lexicographical editing. Primal Testament (2016) is his first book of poetry.

He married Anne Charlotte Begor in 1968 and they have three children, Susannah, David, and Ruth, and a grandson, Cameron. He has lived in Etobicoke since 1971.