For some years following, Grant MacEwan held senior positions with the University of Saskatchewan and the University of Manitoba. Before taking the post of Dean of Agriculture at Manitoba, he was Professor of Animal Husbandry and Farm Superintendent at the Saskatchewan University. Through the years he became widely known across Western Canada for public service, especially in judging livestock at fairs and exhibitions, writing, broadcasting (radio), and lecturing.

After 23 years of university work, he moved to Calgary in 1951, to begin a new life and new career. In the Alberta city, he became involved in political life and served on the Calgary City Council for 12 years - nine as an alderman and three years as Mayor. From 1955 to 1959, he was a member of the Provincial Legislature and in the last part of that period was Leader of the Liberal Opposition. Appointed Lieutenant-Governor of Alberta, he took office on January 6, 1966. As the Queen’s representative for the next eight and one half years, he made a special effort to take the office to rural and remote parts of the province. Statistics reveal that he averaged well over a public function a day, seven days a week for eight and a half years. His travels accounted for over a quarter million miles on the official limousine, not to mention countless bus, train, and air trips to include almost every village and hamlet in Alberta.

Grant MacEwan was the recipient of the following honourary Doctor of Laws degrees: University of Alberta, 1966; University of Calgary, 1967; University of Brandon, 1969; University of Guelph, 1972; and the University of Saskatchewan, 1974. In addition, Edmonton community college Grant MacEwan College was named in his honour when it was established in 1971. In 1972 he was recipient of the Grant MacEwan Community College Honourary Diploma; 1974 the Order of Canada; 1982 he received the Alberta Order of Excellence; 1985 the Governor General’s Conservation Award; in 1987 the SPCA Zeke Young Memorial Award; in 1988 the Sir Frederick Haultain Prize; Citation for Canadian Citizenship 1991; Honourary Chair, Dr. J.W. Grant MacEwan, MacEwan Environmental Studies Institute; and in 1993 The Emerald Award. The College continues to celebrate Grant MacEwan Day in February to recognize the college namesake and to promote his good works.

Associated with many groups and organizations, Grant MacEwan was Honourary Chairman of the Historical Society of Alberta (HSA); Patron of the Calgary Burns Society and Alberta Naturalists Society; Past President of the Calgary Foundation; North American Chancellor of the International Society for Animal Rights; affiliated with the MacEwan Wilderness Hikers Association and the SPCA in Calgary, Red Deer and Edmonton; Honourary Fire Chief of the Calgary Fire Department and Honourary member of B’nai Brith; a member of the Manitoba Agricultural Hall of Fame, and was an honourary bus driver on the MacEwan Coach 956 Greyhound Bus dedicated to him by Greyhound Lines of Canada Ltd. in 1990.

As an author, Dr. MacEwan was a regular contributor to various publications and saw over 55 books published, most of which relate to the history and development of western Canada, western biography and conservation. Some of the titles currently available include such works as: Fifty Mighty Men, And Mighty Women Too, Memory Meadows, John Ware’s Cow Country, Buffalo, Sacred & Sacrificed, Coyote Music, and Watershed. He was honoured on May 6, 2000 by The Writers Guild of Alberta with the Golden Pen Lifetime Achievement Award.

In 2001, the Government of Alberta created the Grant MacEwan Young Writers' Scholarship and the Grant MacEwan Author's Award to honor the life and contributions of this popular Alberta resident.