Manpreet also qualified for the World Championship in London by virtue of being Asian Champion.
Seasoned Vikas Gowda, a last minute entry into the squad, won bronze medal in the men's discus throw event.
Manpreet, who turned 27 today, upstaged defending champion Chinese Guo Tianqian to give herself a perfect birthday gift at the packed Kalinga Stadium.
Tianqian took the silver with a best throw of 17.91m while Aya Ota of Japan got the bronze with 15.45m.
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The Asian Championships winner get an automatic berth for the World Championships to be held in London next month but Manpreet, who originally hails from a village near Patiala in Punjab, had already qualified for the global flagship event with her own national record-improving effort of 18.86, In China.
However, in the men's discus throw, Vikas Gowda failed to defend his title but grabbed a bronze with a best effort of 60.81m.
Earlier, Manpreet, who returned to the circuit last year after taking some time off due to the birth of her first child, said she was happy to have crossed the 18m mark.
"This is the second best throw of my career and I am very happy for this performance. Before the event, I told myself that I should go beyond the 18m mark and anything extra beyond that would be satisfied," she said after having a lap of honour of the Kalinga Stadium drapped wit the tri-colour.
The United Sates-based Indian had to appear for a trial to test his fitness, which he subsequently underwent, to come up with a best throw of 57.79m.
His participation was initially in doubt before he was clear at the eleventh hour to take part in the championship.