MacNeil was born in 1931 at New Waterford, Nova Scotia.
He graduated from Saint Francis Xavier University with an arts degree in 1953, and an education degree in 1954.
He represented the electoral district of Cape Breton Centre in the Nova Scotia House of Assembly from 1989 to 1998. MacNeil entered provincial politics in 1989, running as the Liberal candidate in a Cape Breton Centre by-election. Defeated by seven votes on election night, the number was reduced to two when official results were announced.
A second by-election was held on August 28, 1990, with MacNeil winning the seat.
MacNeil did not seek re-election in 1998.
He was a member of the Nova Scotia Liberal Party. He was re-elected in the 1993 election, and served as a backbench member of John Savage"s government.