Beginning in her forties, Hiong entered into social work, dedicating herself to women's advocacy programs. She later stated she was strongly influenced by her Baháʼí Faith, which promotes equality of all people. In 1952 she met activist Shirin Fozdar, and together they, along with Checha Davies, founded the Singapore Council of Women on 4 April 1952. Throughout the 1950s, Hiong and Fozdar worked to criminalize polygamy, advocate for child care and safer conditions in the workplace, and pressed the government to begin reforms to prostitution law. Hiong also combated what she described as "barbaric and silly" traditions regarding foot binding. The Singapore Council of Women was involved in the passage of the Women's Charter in 1961, which promoted monogamous marriage, the rights of husbands and wives, and reforming divorce laws as to benefit both parents and children.
