Born in Montreal, Quebec, Canada, his father, Daniel Johnson, Sr, served as premier of Quebec from 1966 to 1968. His brother, Daniel Johnson, Jr, served as premier of Quebec for nine months in 1994.
Each of the Johnsons led different political parties: Daniel Sr was leader of the conservative Union Nationale party, and had an ambiguous position on the question of independence for Quebec; Pierre-Marc was leader of the separatistPQ; and Daniel Jr was leader of the federalistQuebec Liberal Party.
Pierre-Marc followed PQ founder René Lévesque as leader of the party and as Quebec premier, but was defeated by the Liberals, led by Robert Bourassa, in the 1985 Quebec election.
Pierre-Marc Johnson has both a law degree and a medical degree. He currently is a Professor of Law at McGill University in Montreal, Quebec.