After his education at Maliyadeva College Kurunegala he joined the Sri Lanka Army on 6th February 1980. Commissioned as a 2nd Lieutenant on 18th July 1981 he was posted to the Sri Lanka Light Infantry. Lieutenant General Ratnayake, a keen athlete since his early school days was the President of the Sri Lanka Amateur Athletic Association and served as a Council member the Sri Lanka Rugby Union. Lieutenant General Daya Ratnayake is married to Damayanthi and the father of two sons and a daughter.
He also served as the Commissioner General, Rehabilitation of former LTTE combatants and Colonel of the Regiment, Sri Lanka Light Infantry (SLLI). His dedication and contribution for Rehabilitation of ex-LTTE combatants under Ministry of Justice has won him plaudits from all quarters both at local and international levels.
Lieutenant General Ratnayake, served as Military Spokesman between 2004-2006. He served as Commander, Forward Maintenance Area (North) from August 2007 to August 2009. Lieutenant General Ratnayake was also the General Officer Commanding, 23 Division from December 2005 until up to August 2007 during the Humanitarian Operations in the East. He had been serving as the Chief of Staff of the Sri Lanka Army since 10th January 2010 until he took office as 20th Commander of the Army.
Lieutenant General Ratnayake, was a keen athlete in his school days carved a niche for himself in the field of sports in the Army.He was the President of the Athletic Association of Sri Lanka in 2012, and currently serves as a council member in Sri Lanka Rugby Union.
Lieutenant General Ratnayake is the recipient of the Weera Wickrema Vibushanaya (WWV), Rana Wickrama Padakkama (RWP) (Awarded four times for Exceptional Gallantry), Rana Sura Padakkama (RSP), Uththama Seva Padakkama (USP )and Desha Puthra Padakkama (DPP).
Lieutenant General Rathnayake has undergone a number of local and foreign training courses during his illustrious career. Commando Officers Course (India), Infantry Young Officers Course (India), Battalion Special Weapons Course (India), Infantry Staff Officer Course (USA), Junior Commander Course (India), Staff Course (Bangladesh), Senior Commander Course (India), Infantry Course (USA), Management Course (India) and National Defence University Course (China) and is presently reading for a PhD at the Kotelawala Defence University.
නව යුද හමුදාපතිවරයා වැඩ බාරගනී….
මෙරට 20 වන යුද හමුදාපතිවරයා ලෙස ලුතිනන් ජනරාල් දයා රත්නායක මහතා අද එම ධූරයේ වැඩ භාර ගත්තේය. දයා රත්නායක මහතා කැඩෙට් නිලධාරියෙකු වශයෙන් 1980 වසරේදී ශ්රී ලංකා යුද හමුදා නිත්ය බල සේනාවට එක් වී සිය හමුදා දිවිය ආරම්භ කළේය. වීර වික්රම විභූෂණ, රණවික්රම, රණශූර ඇතුළු පදක්කම් රැසක් හිමිකර ගැනීමට ඔහු සමත් විය. කළක් ඔහු හමුදා ප්රකාශකවරයා ලෙස ද කටයුතු කළේය. ලුතිනන් ජනරල් දයා රත්නායක මහතා නැගෙනහිර මානුෂීය මෙහෙයුම ආරම්භවීමත් සමගම වැලිකන්ද 23 වැනි පාබල හමුදා සේනාංක මූලස්ථානයේ සේනාංකාධිපති වශයෙන් පත් කෙරුණු අතර නැගෙනහිර ප්රදේශයේ ත්රස්තවාදය තුරන් කිරිමට විශාල කාර්ය භාරයක් ඉටු කළේය. යුද හමුදාපතිවරයා ලෙස පත්වන තෙක්ම දයාරත්නායක මහතා කටයුතු කළේ, ශ්රී ලංකා යුද හමුදාවේ මාණ්ඩලික ප්රධානීයා ලෙස ය.