At the Hangzhou Aquatic Sports Arena, Hoang finished the men's 800 m freestyle event in 7 minutes and 51.44 seconds, which was 0.21 seconds faster than the Olympic standard time.
The result was 2.88 seconds faster than his own at the 2018 tournament, which also won him the bronze medal.
His career-best was 7 minutes and 50.20 seconds when he competed at the 2018 Youth Olympics.
Cyclist Nguyen Thi That and shooter Trinh Thu Vinh are other Vietnamese athletes who have qualified for the 2024 Paris Olympics.
Earlier at the 2023 Asian Games, Hoang placed fourth in the men's 1,500 m freestyle with a time of 15 minutes and 4.06 seconds, and failed to defend his silver medal in the event.
"I have regained my form and did quite well this time," Hoang said after the 800 m event. "I reached the target of winning a medal and I'm feeling so delighted."
South Korea's Kim Woo-min won the gold medal in men's 800 m freestyle with a result of 7 minutes and 46.03 seconds, 2.33 seconds faster than the previous Asian Games record set by China's Sun Yang.
Chinese swimmer Fei Liwei won the silver medal in 7 minutes and 49.90 seconds.
Hoang, born in 2000, is currently Vietnam's number one swimmer. He's holding the national and Southeast Asia record in the 800 m and 1,500 m freestyle. He won gold at the Youth Olympics, silver and bronze at the Asian Games, along with 11 SEA Games gold medals.