His family
Kotakadeniya married his university sweet-heart Somawathie Herath in 1969. She joined the Ceylon Administrative Service in 1967 and retired in 2002 as Additional Secretary Public Administration. She was denied her rightful promotion as a Secretary as a result of unjustifiable prejudices caused by her husband's fortitude and forthrightness as a Police Officer. When Kotakaeniya was accused by the UNP Government in 1981 for complicity in the Naxalite coup-de-etat and was alleged to have been made IGP by Wijaya Kumaratunga, Mrs Kotakadeniya was unceremoniously removed from the post she held in the Cultural Ministry and dumped in the "pool". Nevertheless when it became clear that the alleged coup was a figment of some one's imagination she was fished out of the "pool" and went on to hold several reputed posts in the Administrative Service. She was the first lady to hold the posts of Commissioner of Motor Traffic and the Post Master General. She had the courage to withstand the threats made by trade unions that went on strike against her plans to reform the postal service which was a den of corruption. She was reputed to be an iron lady which quality enabled her to bear and share the trials and tribulation that her husband was subjected to endure in his career.

They have two children- a son and a daughter- Indika and Samanmalee. Indika is a senior software engineer working in the USA. The daughter was a national athlete and gave up her professional career to look after her three children and resides in Abu Dhabi with her husband- Suraj- who is a commercial pilot.

Kotakadeniya hails from a Ranaviru Family. His cousin, Group Captain H.M.Sagar Kotakadeniya is the Base Commander of the Anuradhapura Air Force Camp. Captain Erandaka Ratnayake of the Sri Lanka Army is his wife's sister's son, who is now disabled due to injuries received in the battle field in Jaffna. Major General (Rtd)Ananda Weerasekera and Rear Admiral (RTD) Sarath Weerasekara are his close relatives.