Born in Edmonton, Anderson ran as a Progressive Conservative candidate in the 1979 Alberta general election. He won the electoral district of Calgary Currie, defeating three other candidates. He was re-elected to his second term in the 1982 Alberta general election, winning the popular vote. Anderson stood for a third term in the 1986 Alberta general election. He won that election defeating three other candidates, but his vote share decreased.
After the election, Premier Don Getty appointed Anderson as the Minister of Culture and Multiculturalism and Women's Issues. He held this position until 1987, when he became Minister of Municipal Affairs and Housing. Anderson ran for his fourth and final term in the 1989 Alberta general election. He won election defeating two other candidates. After the election, he was appointed as Minister of Consumer and Corporate Affairs, holding that post until Ralph Klein became Premier in 1992. He also served as deputy house leader and was the primary lead for the Alberta legislative committees on Canada's constitution and Senate reform. Anderson retired at dissolution of the Alberta Legislature in 1993
After leaving politics, Mr. Anderson worked in Russia aiding cities in developing democratic systems; in Peru establishing fairness and protection of individual rights, twice in the Ukraine observing elections, and in India advising on mental health. Since 2000, he has served as Honorary Consul, and now Consul General for Thailand, responsible for Alberta, Saskatchewan and Manitoba. A Commander of the White Elephant (Thailand), he has also received the companion Medal (Thailand).
Mr. Anderson has served as president of the Canadian Mental Health Association in Alberta and on its national executive. He was a director of the Mental Health Commission of Canada, and has worked with other mental health advocacy organizations including the Assured Income for the Severely Handicapped (AISH) panel supporting the provision of financial and health benefits to eligible Albertans with a disability. As Commissioner of the Edmonton Police Commission from 2006-2012 and chair of all Alberta Police Commissions, he initiated mental health training for police.
As founding chair of the Alberta Alliance for Mental Illness and Mental Health, Mr. Anderson united sixteen organizations in the governance of mental health. He has been an advisor to organizations including ]]the psychiatric department of the University of Alberta]], he was founding chair of the Lieutenant Governor's Circle on Mental Health and Addictions, and created the Chimo Project providing animal assisted therapy for people with mental illness.
He received the Hero's award for pioneering the Chimo Project as well as a Best West Award for the best radio show, Youth in Trouble. A recipient of the C.M. Hincks Award from the Canadian Mental Health Association, he has also been awarded the Alberta Centennial Medal, Queen's Diamond Jubilee Medal, 125ᵗʰ Anniversary Commemorative Medal and Canada's Sovereign's Medal for Volunteers.
Mr. Anderson is currently planning to work with governments, hospitals, and other agencies in creating a program that uses animals to foster better mental health. He recently joined the board of the Royal Institute for Mental Health Research in Ottawa.
Dennis Anderson will receive an Honorary Doctorate of Law from the University of Alberta this 2017.