Fitzgerald rose to prominence in the game, and made his test debut for against Australia on 3 June 1979, during an Irish tour of Australia. He captained Ireland to the Triple Crown in 1982 and 1985, and the Five Nations Championship in 1983. Fitzgerald's last test came against Scotland on 15 March 1986 in that year's Five Nations Championship. In total, Fitzgerald received 22 competitive and three friendly caps for Ireland. He scored once, a try against Wales, in the 1980 Five Nations. Fitzgerald also captained the British and Irish Lions team on their 1983 tour, when the team travelled to New Zealand and were beaten in each test against the All Blacks.