John Michael Alfred McMahon (21 February 1914 – 19 May 1975) was an Australian politician and a member of the New South Wales Legislative Assembly from 1950 until 1968.

He served in the Second Australian Imperial Force in the Engineers' Corps from 1943 to 1945 and reached the rank of Lance Sergeant.

[3][4][5] McMahon entered the New South Wales Parliament at the 1950 state election as the labor member for Balmain.

McMahon was a member of the governments of Joseph Cahill, Robert Heffron and Jack Renshaw.

He died age 61 in 1975 and was buried at Field of Mars Cemetery, East Ryde, following a service at St Joseph's Church, Rozelle.