Simon Willis, a 43-year-old Englishman is set to join SLC with a two-year contract.
Sumathipala said the Sri Lanka A team, the development squad, under 23 and under 19 squads will be working under him. All SLC contracted coaches except the national coach would be reporting to him.
The announcement came as Sri Lanka suffered a three-day drubbing at the hands of England in the first Test at Headingley.
Their reversals began in 2015 with home defeats to India and Pakistan while also losing the number one ICC ranking for T20 early this year.