In 1929 he began working as a laboratory assistant at the Rapson Tyre & Rubber Company while studying chemistry and accounting part-time at Launceston Technical College.

[1] In 1930, during the Great Depression, O'Byrne travelled to Queensland from Melbourne on foot where he spent ten years working a variety of jobs including drover, fencer, bullock driver, tank sinker and station overseer.

[2] He joined the Australian Workers' Union in 1935 and became a committed socialist, influenced by the writings of G. D. H. Cole, Harold Laski, and George Bernard Shaw.

The fact that there was not one dissent from his rulings, nor any vote of no confidence, is a testament to his performance and the high regard in which he was held by those on both sides of the chamber.

[citation needed] On 26 January 1984, O'Byrne was made an Officer of the Order of Australia "for service to politics and government".