Colombo - Visitors still have to obtain a visa on arrival, but the government has waived the fee from August 1.
The concession for tourists from 39 nations was suspended after three churches and three luxury hotels were bombed in Colombo on April 21 killing 258 people, including 45 foreigners.
"As the security situation has improved, the cabinet of ministers decided to revive the visa-free scheme and also extended it to seven more countries," the government said in a statement.
A tourism official said foreign governments have relaxed travel advisories for Sri Lanka since the attacks.
There has also been a lift in the number of arrivals, which nosedived soon after the bombings blamed on a home-grown jihadist group, the official said.
The new countries added to the expanded scheme -- which already allows travellers from the European Union, Australia and the United States to enter Sri Lanka without a visa -- include China and India.
Visitors still have to obtain a visa on arrival, but the government has waived the $35 fee from August 1.
Sri Lanka initially projected a 30 per cent dip in the number of foreign holidaymakers after the attacks.
The following month the number of tourists plunged to 37,800, down from 166,975 in April, according to official figures.
But they improved last month with some 63,000 visitors, although numbers are still down from 146,828 in June 2018.
Sri Lanka welcomed a record 2.33 million tourists in 2018, and was named the world's top travel destination for 2019 by the Lonely Planet travel guide.