He was born in Brooklet, near Hinchinbrooke, Quebec, the son of Frederick Malcolm Rennie, farmer, and Maria Carter.
He took correspondence courses from Queen's University and received a diploma in the field of life insurance in 1932.
He was elected to the Legislative Assembly of Quebec for the Union Nationale in Huntingdon in a by-election on July 23, 1947.
He was deputy whip for the Union Nationale from 1948 to 1952, and a member of the Protestant Board of Education from 1949 to 1951.
He married Margaret Ruth Davison, daughter of Walter Cecil Davison, merchant, and Margaret Gibb, on December 28, 1940 at St. Matthew's Anglican Church, [Montreal, Quebec].