He served as the Chief of Staff of the Sri Lanka Navy and Joint chief Hydrographer to the Government of Sri Lanka,[1] former Commandant of the Naval and Maritime Academy and Commanding Officer, 4th Fast Attack Flotilla.

[2] Having joined the Sri Lanka Navy in 1986 as an Officer Cadet, Jayarathna received his basic training at the Naval and Maritime Academy, where he topped his batch winning the Sword of Honour and was selected for the International Midshipman Course at Britannia Royal Naval College from 1988 to 1989.

He was commissioned a Sub Lieutenant in 1988, and was attached to the 4th Fast Attack Flotilla on his return from the United Kingdom, serving in the Dvora class fast patrol boats that became the primary offensive weapon of the navy against the Sea Tigers as the Sri Lankan Civil War escalated.

He attended the Army Command and Staff College gaining the psc qualification and a Master's in Defence Studies from the University of Kelaniya in 2001.

[2] Having completed the national defence course at the PLA National Defence University, he served as Deputy Area Commander Northern Naval Area, Deputy Director General Sri Lanka Coast Guard, Deputy Area Commander Eastern Naval Area and Port Facility Security Officers of Trincomalee Port, Director Naval Training, Director General Training and Director General Operations.