Ernaga played first-class cricket for Singha Sports Club in Sri Lanka before having to retire from first-class cricket due to a shoulder injury. Previously he had played for Sri Lanka U19s including in the mini World Cup in India in 1998.

Eranga is a specialist spin bowling coach who runs a spin bowling masterclass programme at junior and senior levels. He also runs various elite player development programmes. He has played surrey premier league cricket for Wimbledon cricket club.