Ong Yoke Lin was born on 23 July 1917 in Kuala Lumpur, he attended Pudu Girls' English School and later Victoria Institution, where he was contemporaries of, among others, Yahya Abdul Razak, Lee Siew Choh, Yaacob Latiff and Mahmood Ambak, the father-in-law of Abdullah Ahmad Badawi, the fifth Prime Minister of Malaysia.

In 1952, he and Yahya Abdul Razak mooted the idea of an alliance between MCA and the United Malays National Organisation (UMNO) for the Kuala Lumpur Municipal Council elections.

Following the overwhelming support shown for the Alliance Party during the elections and the forming of the government, the Tunku led the Merdeka Delegation to London which successfully negotiated independence from the British.

[3] On 31 August 1957, Omar was appointed to the first Rahman cabinet of the newly independent Federation of Malaya, holding the Labour and Social Welfare portfolio.

Tun Omar was married to Toh Puan Dr. Aishah Chan binti Abdullah, also a Chinese Muslim convert and had three children.