Fisherman Pham Viet Khai found the turtle caught in his net while fishing at sea at around 8 pm on September 28.
He brought the animal ashore for temporary care and alerted the Tam Giang Tay Border Guard Station.
Border guards and Tan An Commune police examined and cared for the turtle before releasing it back into the sea on the morning of September 29.
Earlier, on September 14, another local fisherman handed over a green sea turtle weighing about 3 kg after finding it while fishing. The animal was later released into the wild.
Nguyen Minh Nhong, head of the Tam Giang Tay Border Guard Station, said green sea turtles were rare marine animals that played an important role in marine ecosystems and faced a serious decline in numbers.
He added fishermen voluntarily handing over rescued turtles for release reflected growing awareness of wildlife and marine biodiversity conservation.