He was the only president of the short-lived Second Republic of Korea, and served as little more than a figurehead due to its nature as a parliamentary system.

Having entered politics after World War II, Yun served as Secretary to Korea's Chief of Staff in 1947, and was Mayor of Seoul in 1948.

He was a son of Yun Chi-so (윤치소, 尹致昭, 1871–1944) and Lady Yi Beom-suk (이범숙, 李範淑, 1876–1969).

In the aftermath of the authoritarian excesses of Rhee's regime, South Korea had switched to a parliamentary system; thus, Yun served merely as a ceremonial president.

Following Park Chung Hee's coup in 1961, Yun stayed in his post in order to provide some legitimacy to the new regime, but resigned on 22 March 1962.

He was accorded a state funeral by President Roh Tae-woo and was interred at Seonsan, Asan, South Chungcheong Province.