After leaving parliament, Fadden pursued business interests across a wide range of industries. He visited Japan twice in 1959, and was appointed as the representative of a Japanese company hoping to acquire a licence to export iron ore from Western Australia. The deal fell through, which he attributed to political interference. Fadden was chairman of Centenary Estates Limited, which built the housing development that became known as the Centenary Suburbs. He took up several company directorships, including with the real estate firm Hooker Finance and the ice-cream manufacturer Toppa. He also worked as a consultant for a sugar mill in Tully, Queensland, and invested in an iron ore deposit at Mourilyan, Queensland. In 1960, he was commissioned by the state government to produce a report into the viability of Central Queensland ports.