He was born in Goondiwindi to Henry McKechnie and Heather May, née Coulton.
He worked as a station hand from 1957 to 1958 and a property manager from 1961 to 1968 before becoming a grazier in Charters Towers.
In April 1974 he became electoral secretary to his father, who was the Country Party member for Carnarvon in the Queensland Legislative Assembly.
In 1983 he was appointed Minister for Tourism, National Parks, Sport and the Arts, moving to Industry and Technology in 1986 and to Family Services and Welfare Housing in 1987.
In January 1989 he became Minister for Transport, but in September announced his retirement from politics to care for his wife, who was ill. McKechnie died in Toowoomba in 2011.