Ouseph, 29, beat Japan's Sho Sasaki 21-15 21-9, dominating throughout in a promising display.
Compatriot Kirsty Gilmour failed to progress in the women's draw however, losing 21-12 17-21 16-21 to Linda Zetchiri of Bulgaria.
"I hope I'm only at the start of my career and I've got many more lessons to learn on the way," she said.
Britain's Rajiv Ouseph won his second pool game to progress to the last 16 of the Rio men's badminton.