A right-handed batsman who often opened the innings, Onyons made an inauspicious first-class cricket debut, bagging a pair at the Sydney Cricket Ground on 25 January 1919 against NSW.[1]
He didn't play another first-class match until exactly eight years later when he captained Victoria in a game against Tasmania at the MCG. Despite batting at number eight down the order he made 128.[2]
In a good 1928/29 Sheffield Shield season, Onyons made 582 runs at 72.75 with four hundreds from four games.[3]