The post is one of the oldest in the civil service as it had been established by the British during the colonial era.

In 1957, Weerakoon entered the Tellijawila Central College, where he successfully completed the Higher School Certificate.

Weerakoon completed his postgraduate studies at The Hague University in Netherlands, the University of Hawaiʻi in United States and at the United Nations Asia and Far East Institute (UNAFEI) in Japan.

Sanath's Grandparents were Don Nicholas Rathnayake Weerakoon & Dona Abeysekeara Pathiranalage Gimara.

Sanath Weerakoon married Asoka Palihena in 1972 and they have three children: Thushani, Dushan and Janake.