He was born at Killaloe, County Clare to bootmaker Patrick Minahan and Mary, née Murphy.
[3] Proportional representation was introduced in NSW for the 1920 election and Minahan was nominated by the Labor Party for the five member seat of Sydney.
Shortly before polling day however, he and Scott Campbell had their endorsement withdrawn because they signed a pledge for the unconditional release of twelve imprisoned members of the Industrial Workers of the World.
[6] He was re-elected fifth at the 1922 election,[7] Defeated in 1925, he returned some months later after to fill the vacancy caused by John Birt's death.
[9] Minahan stood against Premier Jack Lang as an Independent Labor candidate for Auburn, but was defeated.