He attended elementary school at the Cape Croker Indian Reserve school until the age of 10, after which he attended St. Peter Claver's Indian Residential School in Spanish, Ontario. He left school for a time before finishing the ninth grade, but soon learned that it would be difficult to support himself without further education. In the meantime, St. Peter Claver's had gained a new Father Superior who reorganized the school as Garnier Residential School for Indian Boys to deliver a secondary school education, instead of as a trade school. In 1950, Johnston graduated valedictorian from Garnier and then attended Loyola College in Montreal where he graduated with honors, earning a B.A. in 1954. An account of his school years can be read in Indian School Days.

From 1955 through 1961, Basil Johnston was employed by the Toronto Board of Trade. He received his Secondary School Teaching Certificate from the Ontario College of Education in 1962, and took a position teaching history at the Earl Haig Secondary School in North York until 1969. He then joined the Ethnology Department of the Royal Ontario Museum where he worked for the next 25 years with a mandate to record and celebrate Ojibwa (Anishinaabe) heritage, especially language and mythology. His writings began appearing in print in 1970. The first essay, "Bread Before Books or Books Before Bread," which appeared in The Only Good Indian: Essays by Canadian Indians, recounts events contributing to the deterioration of the Native American culture. For the Indian and Northern Affairs Canada, Johnston wrote the Ojibway Language Course Outline and the Ojibway Language Lexicon in 1978. Basil is a fluent speaker, scholar, and teacher of the Anishinaabe language who writes in both English and Anishinaabemowin. He is often sought as a translator, perhaps because his translations display a sensitivity to both the Ojibwa and English languages. Since the key to understanding culture is language, to provide this key, Basil Johnston has developed audio programs on cassette and CD.

Back in 1968 a grade 5 student, after studying Indians in-depth for five weeks, asked Basil Johnston, a visitor to the school, "Is that all there is to Indians, Sir?" Since that time Basil has written 15 books in English and 5 in Ojibwemowin to show that there is much more to North American Indian life than social organization, hunting and fishing, food preparation, clothing, dwellings and transportation. In addition, he has written numerous articles that have been published in newspapers, anthologies and periodicals. In 1978, he developed the script for the film, The Man, the Snake and the Fox, still available from the National Film Board of Canada. Basil travels extensively throughout Canada and the U.S. to speak about the Ojibwa culture and language. He often visits Canadian and U.S. Ojibwa reserves and reservations and schools where he continues to pass down the stories, customs, and history of the Ojibwa people in the Ojibwa oral tradition.

For his work in preserving Ojibwa language and culture, he has received the Order of Ontario and Honorary Doctorates from the University of Toronto and Laurentian University. Basil has also received the 2004 Aboriginal Achievement Award for Heritage and Spirituality.