Walter Pitman was born in Toronto, Ontario. He received a Bachelor of Arts in 1952 and a Master of Arts in 1954 from the University of Toronto. He was a high school teacher when he was nominated by Peterborough's New Party Club to be their candidate in a 1960 by-election, which he won. Pitman's victory energized the New Party movement, and, in 1961, the CCF and CLC formed a new political entity, the New Democratic Party. Despite Pitman's new found political celebrity he narrowly lost his seat in the 1962 election by 564 votes. He was defeated again in the 1963 election by 804 votes.
In the 1967 Ontario provincial election, Pitman won the Peterborough seat for the Ontario New Democratic Party. As a Member of Provincial Parliament (MPP), Pitman unsuccessfully ran to replace Donald C. MacDonald as leader of the provincial NDP. He came in second to Stephen Lewis at the 1970 Ontario NDP leadership convention. He lost his seat in the 1971 provincial election. Following his electoral defeat, Pitman returned to education as director of the Ontario Institute for Studies in Education, and later became the president of Ryerson Polytechnical Institute between 1975-1980. Between his federal and provincial political careers, he was dean of arts and science at Trent University. Pitman is also a former president of the Canadian Civil Liberties Association. In 1992, he was made an Officer of the Order of Canada. He was also awarded the Order of Ontario.