Thirteen-year-old Swapnali finished second behind gold winner Zoe Bowden of the host nation, while Nuralia Mohammed Shamsir, also of Malaysia, won the bronze in the 15 years-and-under category for girls.
Swapnali did the 300m swim in 0:05:01 seconds, cycled 8km in 0:16:41 and the 2km run in 0:11:23 for an aggregate time of 0:33:05 seconds at the Water Sports Complex, yesterday.
"I am very happy with my performance. The competition was tough and I gave it my all towards the end to push Nuralia to the third place," said Swapnali from Malaysia.
"I tried not to make the mistakes I had in the Asian Cup and this was a much better effort."
Fifteen-year-old Bowden, who recently won the Asian Cup International Triathlon in the Philippines, clocked 0:29:17, while Shamsir was third in 0:33:46.
There were 169 participants from all over the world including, Macau, Thailand, China, Japan, Great Britain, Australia, Netherlands, USA and Malaysia.