Sanusi was one of the few ulama who had a good command of Malay, Arabic and English during his time. From 1922 to 1931, he attended Victoria Bridge School and then Raffles Institution. In 1929, due to his excellent results in the Senior Cambridge examination, he managed to skip two grades. Sanusi went on to study Islam and Arabic from his grandfather, the Mufti of Indera Giri, at Safat, Sumatra, Indonesia from 1931 to 1932.
In 1968, Sanusi was appointed as Singapore's first Mufti as well as the President of Syariah Court, holding both posts concurrently. In 1972, he stepped down as the Mufti.
He wrote many books, such as "Kamus Istilah Islamiah Sanusi", "Taman Mu'minin" and "Mengenal Islam dan Hubungannya Dengan Sains & Teknologi".
