South Korea made beat Japan 2-1 in the final on Saturday thanks to extra-time goals from Lee Seung-woo and Hwang Hee-chan to finish first place for the first time since 1986.
The Tottenham forward was apologetic for missing the start of the Premier League action to feature in the Under-23 tournament in Indonesia, but the club gave him permission to go knowing a gold medal would seal his release from mandatory service for his country.
Athletes who win gold at the Asian Games - silver or bronze is not enough - are exempt from the service, which lasts at least 21 months, meaning it was a narrow escape for captain Son and his team-mates.
Round by round the pressure has increased for Son and his team-mates and it showed in the final as they took their time to break down Japan.
South Korea dominated the opening half and saw Hwang Ui-jo waste a glorious chance to break the deadlock, and their profligacy continued after the restart.
Son was guilty of failing to take clear-cut chances, and when he turned provider Ui-jo, the tournament's top scorer, was again unable to convert.
An extra 30 minutes was needed to separate the two sides and fittingly the Spurs star was at the heart of securing South Korea's triumph.
The 26-year-old embarked on a mazy dribble three minutes into extra time before a heavy touch ran to Seung Woo-lee, the winger lashing home from inside the box.
Another Son delivery helped wrap things up, Hwang Hee-chan heading home to secure the gold medal - despite Ayase Ueda's late consolation - and all-important exemption from national service.