Irwin's first World Cup race was the downhill at Schladming, Austria on December 22, 1973 where he placed 14th. Two years later at Schladming, he won the downhill event in a time of 2:00.84 beating the second-place finisher, Klaus Eberhard by almost two seconds.
Irwin reached the podium again in 1982 with a third-place finish at the World Cup downhill in Whistler, B.C. behind winner Peter Müller, and team mate Steve Podborski.