The world no.11 Srikanth won 22-20 21-16 in a 45-minute clash against the world no.6 Chinese, who is also a two-time All England champion.
The triumph is his second successive after clinching the Indonesia Open Super Series Premier title last week.
"As a whole I played very well, but since I arrived in Sydney I have gastroenteritis and have had diarrhoea, so I have not been at my best physical condition. But since I made the final I wanted to continue to play as well as I could," an ecstatic Srikanth said after the victory.
Entering the summit showdown, Srikanth was only the fifth player in the world to contest three successive Super Series finals (Singapore and Indonesia prior to this).
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The Indian, a semi-finalist in the last edition of the tournament, was the one to grab the early lead. Following a sedate start, Srikanth capitalised on his opponent's rather sluggish game to clinch a 10-6 lead.
But perhaps jolted by the lead he had conceded, Long gathered himself just in time, starting with a deftly-placed smash, to make it 11-11.
The Chinese shifted gears quite suddenly to add pace to the proceedings and his baseline strokes stood out for both ferocity and accuracy.
"I'm playing better after the Sudirman Cup. I should thank my physio for keeping me fit for these two tournaments. It was tough for me on Tuesday and Wednesday," he said.
And it was this tenacity which got Srikanth a 17-15 lead even though Long continued to breathe down his neck.
But Srikanth did not let the momentum slip, and helped by Long's erratic play, the underdog earned his first game point at 20-19.
Long managed to save that with a rasping smash but Srikanth's perseverance fetched him another at 21-20 when the Chinese was foxed by a low backhand return. This time, Srikanth made no mistake and sealed the first game in 23 minutes.
"There was a long rally early in the second game and after I won that I got more confident. If he had won it he would've kept doing it (rallies)," Srikanth explained.
The see-saw battle continued for a while before Srikanth broke away to lead 6-3, dominating the rallies with his accurately, rather awkwardly, placed shots, which Long found difficult to return.
But it was not to say that Long was completely out of the contest. He did manage to keep the gap in check with flashes of brilliance that make him among the best in the world.
Srikanth did not let the lead slip from that point, raising his game by quite a few notches against an increasingly faltering Long.
It took Srikanth a minute less than the first game to wrap up a rather comfortable victory.
The triumph was a morale-boosting jinx-breaker for Srikanth, who had lost all his previous five encounters to Long.
"I'm just happy to be doing well for now," he said.