In the lead up to the 1964 state election, Peter Garrisson, the Liberal member for Jona's local seat of Hawthorn was disendorsed because he was charged under the Companies Act. Jona won a hotly contested preselection against ten other candidates, and went on to win the seat despite challenges from Garrisson and from Labor (at the time, the seat of Hawthorn included parts of working class Richmond, making it less secure for the Liberals than today).
Jona served as the Chairman of a Select Committee on Road Safety between 1967 and 1973.[4] This committee recommended the mandatory wearing of seatbelts in 1971, which was a world first.[1]
From 1973 to 1976 Jona served as Parliamentary Secretary to cabinet before being promoted by Premier Rupert Hamer to be Victoria's first Ethnic Affairs Minister. From 1979 until the Liberals' defeat at the 1982 election, Jona served as Minister for Community Welfare Services. He also served as shadow Education Minister until his retirement in 1985.[5]
Like many Liberal Party politicians from Victoria, Jona's political views were considered to be small-l liberal. After retirement, Jona criticized the government of Joh Bjelke-Petersen for its "contempt of parliament" and "exercising [of] absolute power" as well as criticizing the current federal Coalition government for its increasingly centralist style of government. .[6]