It was also the Keralite's first title after the triumph in the 2017 US Open.
Prannoy's opponent Christian Adinata of Indonesia conceded the semifinal match following a nasty knee injury.
Kidambi Srikanth went down to Indonesian qualifier Christian Adinata 21-16, 16-21, 11-21 in a men's singles quarterfinal clash.
The rally took place in the decider and lasted for almost four minutes.
World No. 22 Lakshya Sen went down fighting to Ng Ka Long Angus of Hong Kong 14-21, 19-21 in the pre-quarterfinals.
P V Sindhu and Kidambi Srikanth too advanced to the pre-quarterfinals.
It was heartbreak once again in the semifinals for the Keralite as he squandered a one-game advantage to go down 21-17, 9-21, 17-21 to Angus Ng Ka Long.
Sindhu lost to her nemesis Tai Tzu Ying of Taiwan, 13-21 21-12 12-21.
For Saina Nehwal it is consecutive first-round exit in the event.
Tai Tzu-ying beat Sindhu 21-16, 21-16 in the quarterfinal, while Saina was no match for Carolina Marin.