Neeraj registered his season's best performance of 86.47 metres in the final.
Vipin Kashana, the other Indian in the fray, took the fifth spot with an attempt of 77.87m.
Neeraj started with an opening throw of 85.50m before fouling his second attempt.
He had an effort of 84.78m in his third attempt before coming up with the winning mark with his fourth throw.
Later in the day, Jinson Johnson set a new national record of 3 minutes and 37.86 seconds while taking the fifth spot in the men's 1,500m final.
Charles Da'Vall Grice of England beat Johnson to the fourth position by a fraction of a second with a time of 3:37.43.
Troy Doris of Guyana came up with his season's best performance of 16.88m to win the gold medal. Yordanys Garcia (16.86m) will take the silver medal to Dominica while Marcel Mayack took the bronze medal for Cameroon with a personal best mark of 16.80m.
(Only the headline and picture of this report may have been reworked by the Business Standard staff; the rest of the content is auto-generated from a syndicated feed.)