The cuts follow a sharp fall in international energy prices after the United States and Iran agreed to hold talks to bring an end to their conflict.
Sri Lanka had raised petrol and diesel prices by almost 50 percent after the US and Israel launched attacks on Iran on 28 February.
Electricity tariffs were also increased by one-third as authorities sought to pass on higher import costs.
Sri Lanka, which buys in all of its oil and also relies on imported coal for power generation, has warned that any prolonged conflict in the Middle East could threaten a fragile economic recovery.
The government told the International Monetary Fund, which granted a $2.9-billion bailout loan to the island in March 2023, that sustained high energy prices could undermine efforts to emerge from the country’s worst economic crisis.