The move came a day after the country received half a million doses of the AstraZeneca-Oxford University vaccine donated by India and manufactured by the Serum Institute of India.
The Sri Lankan government said 150,000 frontline health workers and 115,000 selected military and police personnel would be the first recipients.
The country’s regulatory body approved the vaccine last week as doctors were warning that frontline health workers should be quickly inoculated to prevent the medical system from collapsing.
The first stage of the vaccination programme will take place over four days at six state-run hospitals in the capital Colombo and two hospitals run by the army.
The health ministry said it would expand the programme to other parts of the country by next week.
The ministry has planned up to 4,000 vaccination centres countrywide.
Sri Lanka has reported 61,585 cases with 297 fatalities since March. Currently it has 300 to 900 new cases every day.