[7] He was educated at the Madawala Maha Vidyalaya in Uva Paranagama where he also pursued his athletics career.

[7] After completing his primary and secondary education at the Madawala Maha Vidyalaya, Mangala joined Sri Lanka Army on 18 January 2000 initially to pursue his training in athletics.

[1] He made his mark in the sport of shooting after claiming a gold medal in the men's 50m rifle prone event during the 2006 South Asian Games.

Samarakoon also represented Sri Lanka at the 2016 Summer Olympics which was held in Rio de Janeiro.

[16] During the 2016 Summer Olympics, he blamed the Sri Lanka Shooting Sports Federation for failing to provide him a suitable shooting kit which made his participation quite difficult when he was slotted to compete in the men's 10m air rifle event.