It was the sixth straight month that Indonesia has recorded a trade surplus and the figure was about double that forecast by economists. It compared to a $450 million excess in April.
The widening surplus was driven by a sharp fall in imports to $11.61 billion, down 21.4 percent from a year earlier, a sign of slowing consumer demand as the G20 economy cools.
Exports fell less steeply, but were still down 15.2 percent year-on-year at $12.56 billion, according to the data from the official statistics agency.
Despite the downbeat figures, policymakers were expected to welcome the growing surplus as they battle to narrow a stubborn current-account deficit.
Indonesia's economy has been slowing in recent times as the price of its key commodity exports slips and demand falls in China, the world's number two economy.
Growth slipped to 4.7 percent year-on-year in the first quarter, its slowest pace in around six years, and well below the government's target of 5.7 percent for this year.