The region should now grow by 5.9 per cent this year and 5.8 per cent in 2018, the Manila-based lender said in a report.
The bank updated its earlier forecasts, released in April, that predicted 5.7 per cent growth for the region this year and next.
"Unanticipated external demand has improved growth prospects for developing Asia," ADB said.
"The resulting boost to net exports all but suspends growth moderation" in China, the region's largest economy, it added.
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China's economy grew by stronger than expected 6.9 per cent in the first half this year, which should help it expand by 6.7 per cent for 2017 and 6.4 per cent in 2018, it added.
The growth outlook for the manufacturing dynamos of East Asia is brighter, with South Korea energised by receding political uncertainty with the election of a new president, it said.
The bank maintained its 7.4 per cent growth forecast for India this year and 7.6 per cent for 2018, primarily from strong consumption, and the rest of South Asia's prospects also remained robust.
ADB upgraded its forecast growth for the former Soviet republics of Central Asia, with Armenia, Kazakhstan and Tajikistan uplifted by manufacturing and mining.
The bank maintained its earlier projections for Pacific island economies.
It revised its inflation outlook for developing Asia by 0.4 percentage points this year to 2.6 per cent, and by 0.2 percentage points next year to 3.0 per cent.
"Ample supply has held world oil prices low despite rising demand, while favourable weather has kept food prices stable.
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