Born in Singapore during colonial rule, Koh studied at Nanyang Girls' High School before marrying Wee in 1936.

During her time as Spouse of the President, she performed philanthropic work for multiple charities and was also known for her fashion, particularly that she frequently wore cheongsams, a Chinese dress.

[3] In 1965, she worked as a food writer for magazine Her World in a column titled "Malaysian Kitchen", writing nyonya recipes.

[3] Whilst Wee worked as a diplomat, Koh often cooked and hosted dinner parties, with Wee's personal assistant stating about Koh that "cooking and managing a formal sit-down official dinner for 20 guests was just as easy as preparing for a one-to-one lunch.

[5] During her time as Spouse, she did philanthropy work and supported charities such as Girl Guides Singapore, Life Community Services Society, and Jamiyah Home for the Aged,[3] serving as the patron of the former from 1985 to 1994.