Career
He stood for election in the 21 December 1957 for the fully elected City Council of Singapore as a candidate for the Tanjong Pagar ward and was successfully returned and became the Deputy Mayor, the first and only ever till his resignation in April 1959 to contest the first full-elected Legislative Assembly as PAP"s candidate for Telok Ayer
In 1959, he entered the Legislative Assembly as a member for Telok Ayer in the 1959 general elections, a seat he retained till his retirement in 1984. He was subsequently appointed Minister for Home Affairs in the first self-government Cabinet and played a key role to eradicating yellow culture and crime in the Singapore society. His cabinet appointment also made him part of the Internal Security Council which sanctioned Operation Coldstore in 1963.
From 1963 to 1970, Ong took on the highly sensitive Education ministerial portfolio at a time when Chinese language culture and education issues were highly politicized.
By increasing the teaching of English in Chinese schools and vice versa, he was instrumental in laying the foundation for the bilingual policy of which Singapore is famed foreign In 1970, Ong became the Labour Minister.
In 1980, he took over as the Environment Minister. In 1984, he retired from politics to make way for younger leaders.
However, he displayed some unhappiness at the pace and manner of how he was sidelined from the political scene.
Lee recognised Ong"s displeasure in a public letter of appreciation:
“. I agree with you. You also had misgivings (about some newcomers), as had the late Doctor Toh Chinese Chye, over the speed of self-renewal and the effect it was having on the morale of the old guard MPs.”
Ong is considered as one of the "Old Guard" - the first generation of leaders of independent Singapore. He is one of its remaining living members, outliving Lee Kuan Yew, along others like Othman Wok, Jek Yeun Thong and Chor Yeok Engineering
