Having posted a modest score of 133 from 19.1 overs, Sri Lanka had little problem in tearing through the Afghanistan line-up, reducing them to 65 all out from 17.4 overs to seal the title at the Yeonhui Cricket Ground.
"This is a great feeling, because this is our first gold medal since 2002," Sri Lanka captain Lahiru Thirimanne said.
"These type of tournaments are good for our young emerging players. This will be a good platform for them.
"I think we'll win gold in the next Asian Games as well."
There was more success for host nation South Korea in Incheon as their men's basketball team replicated the feat of the women by winning gold, holding off Iran to secure the crown with a 79-77 victory.
Action in the Boxing was dominated by Kazakhstan, who saw six fighters claim gold on the final day of action in the ring, Ilyas Suleimenov, Daniyar Yeleussinov, Zhanibek Alimkhanuly, Adilbek Niyazymbetov, Anton Pinchuk and Ivan Dychko all tasting glory.
Shin Jong-hun and Lim Hyun-chul won their respective bouts for seal further gold for South Korea while there were also victories for Otgondalai Dorjnyambuu of Mongolia and Thailand's Wuttichai Masuk.
China concluded matters in the Munhak Park Tae-hwan Aquatics Centre by completing a clean sweep of all the Games' diving gold medals as Qiu Bo won the men's 10-metre platform and He Zi triumphed in the women's 3m springboard.
There was more glory for the medal table leaders in the modern pentathlon with wins in the men's team event and in the men's individual, the latter coming courtesy of a fine performance from Guo Jianli.
Gold in the men's doubles and women's doubles table tennis also went to China, although North Korea were triumphant in the mixed doubles, ensuring their 11th gold of the games.
Iran emerged victorious in the men's volleyball final, beating Japan 28-26 23-25 25-19 25-19, however, their men's and women's kabaddi teams both fell short in gold medal matches with India.
Ali Hasan Mahboob made it a marathon double for Bahrain with his third consecutive Asian Games success in the men's race a day after Eunice Jepkirui Kirwa had taken gold in the women's event.
Seavmey Sorn beat Fatemeh Rouhani of Iran in the women's under-73kilogram Taekwondo final to secure Cambodia's first medal of the Games.
Li Donghua of China was successful in the women's over-73kg discipline, and there were triumphs for South Korea's Kim Tae-hun and Iranian Farzan Ashourzadehfallah in the men's under-54kg and under-58kg respectively.
In sepak takraw Thailand beat South Korea in the men's and women's regu finals while in Karate there were gold medals won by Kazakhstan's Andrey Aktauov and Guzaliya Gafurova, Iran's Amir Mahdi Zadeh, Wen Tzu Yun of Chinese Taipei and Malaysian Syakilla Salni Binti Jefry Krisnan.