Mugo was born in 1942, in Baricho, Kirinyaga District, Kenya. The daughter of two progressive (liberal) teachers, she received a solid primary and secondary education in Kenya. She became one of the first black students to be allowed to enroll in what had previously been a segregated academy. She later attended Makerere University (where she gained her B.A. in 1966), the University of New Brunswick (gaining her M.A. in 1973) and University of Toronto (where she gained her Ph.D. in 1978). She took up a teaching position at the University of Nairobi in 1973, and in 1978 or 1980 became Dean of the Faculty of Arts, making her the first female faculty dean in Kenya. She taught at the University of Nairobi until 1982, and has also taught at the University of Zimbabwe.

Mugo was a political activist who fought against human rights abuses in Kenya. Her political activism led to her being harassed by the police and arrested. Mugo was forced to depart Kenya in 1982 with her two young daughters after becoming the target of official government harassment. She has worked, written, and taught from abroad since she left Kenya. Since 1984 she has been a citizen of Zimbabwe.

Mugo is the founder and President of the Pan African Community of Central New York where she initiated volunteer programs in two prisons. She has been an official speaker for Amnesty International and a consultant for the "Africa on the Horizon" series by Blackside. Currently she is a consultant for many foundations, and on the board of many journals. She also served as chairperson of the board of directors of SARIPS, the Southern Africa Regional Institute for Policy Studies in Harare. She is currently a lecturer in the Pan African Studies Program at Syracuse University.

Mugo is a distinguished poet, and the author or editor of fifteen books. Her work is generally from a traditional African, Pan-African and feminist perspective, and draws heavily upon indigenous African cultural traditions. She has also collaborated with the Zimbabwean writer Shimmer Chinodya in editing plays and stories for adolescents in Shona.

Plays

• The Long Illness of Ex-Chief Kiti, East African Literature Bureau, 1976
• (co-authored with Ngugi wa Thiong'o) The Trial of Dedan Kimathi , Heinemann, 1976

Poetry

• Daughter of My People, Sing!, East African Literature Bureau, 1976
• My Mother's Song and Other Poems, East African Educational Publishers, 1994

Literary Criticism

• Visions of Africa: The Fiction of Chinua Achebe, Margaret Laurence, Elspeth Huxley, and Ngugi wa Thiong'o, 1978
• African Orature and Human Rights, National University of Lesotho, 1991