Wijeysingha became a teacher at
Raffles Institution in 1959, and taught at the school for seven years as a history teacher. His students included
Goh Chok Tong,
Zainul Abidin and
Abdullah Tarmugi. In 1967, he became the principal of Changkat Changi Secondary School. From January 1980 to November 1985, he served as the principal of
Temasek Junior College. From 1986 to 1994, Wijeysingha served as the principal of
Raffles Institution, during which he played a pivotal role in leading the school to independence and coordinated the school's relocation to the
Bishan campus in 1990. He retired from the position in 1994. In 1992, he was awarded the Outstanding Singapore Sinhalese Award. He served as the chairman of the Compulsory Education Board from 2003 to 2007. After retirement, Wijeysingha also published a book on the history of the school, "The Eagle breeds a Gryphon". ==Personal life==