Dunphy was born in 1937 in Peakes Station, Prince Edward Island.[1] Dunphy graduated from the Nova Scotia Agricultural College with a two-year degree in agricultural studies in 1958, and from Macdonald College at McGill University with a Bachelor of Science in agriculture in 1960.[1] He was married to Rita Kenny, and then Marion MacRae-Gillis in 1978. Tom has 4 children Peter, Maggie, Kimberley, and Tracy. As well as 4 grandchildren, Sebastian, Sarah, Liam and Patrick.[1] Prior to entering politics, Tom was a teacher in Prince Edward Island and Quebec. He also worked with Dr Leo Killorn in the PEI addiction treatment center.[1]
Dunphy entered provincial politics in 1986, when he was elected a councillor for the electoral district of 3rd Queens.[2] He was re-elected in the 1989 election.[3] In November 1991, Dunphy was appointed to the Executive Council of Prince Edward Island as Minister of Transportation and Public Works.[1] Dunphy was re-elected in 1993,[4] but was dropped from cabinet following the election.[5] He did not re-offer in the 1996 election.[1] Following his political career, Dunphy worked as a realtor.[1]