In 1920 he appeared three times for the New South Wales Waratahs against the All Blacks scoring a try in his representative debut. With no Queensland Rugby Union competition in place at that time the New South Wales Waratahs were the top Australian representative rugby union side of the period and a number of Waratah matches of the 1920s played against full international opponents were in 1986 decreed by the Australian Rugby Union as Test matches.
He made representative appearances in 1922 against the New Zealand Maori and the All Blacks, played in three Tests against them in 1924 and in five matches against them in 1925. The 3rd test of 1925 played on 23 June at the Sydney Showground was Fox's sole appearance as the national captain. He was solid in further Test appearances against New Zealand in 1926
He was a tremendous lineout forward and one of the senior players for the 1927-28 Waratahs tour of Britain, France and Canada, picked as the tour's vice-captain under Johnnie Wallace. He played in 10 of the first 13 games of the trip until he suffered a severe leg injury in the tour match loss to Oxford University RFC. He was captain in that Oxford game and with no subsititutes allowed, the Waratahs played the second half with 14 men and lost to the students 0-3. He recovered for the last four matches including the international against France where Fox at least enjoyed a Test match victory.
He retired at the end of Waratahs tour.