"It was very tricky out here, quite windy, and I'd never played her before", Konta told Eurosport.
But she got back into the match and levelled it at one set apiece, finally converting her seventh break-point opportunity.
Konta was furious at a decision that went against her as Barty moved 5-4 up and was involved in a heated exchange with the umpire, where she described the call as "a joke".
The 6-3, 3-6, 6-4 victory marked the second WTA title for Barty after her win in Kuala Lumpur previous year, and lifts her to No.16 in the world rankings leading into next month's Wimbledon tournament.
One of Ash Barty's finest victories to date has been overshadowed by a dramatic display of poor sportsmanship from Brit Johanna Konta.
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For a second chance at a WTA title, she'll face Australia's Ashleigh Barty who she beat past year in the quarterfinals. Do you fully understand that?'
It was Barty's first tournament triumph of the year, the second of her career and a demonstration from the former junior Wimbledon champion that she could now even be an outside threat for the senior title at the Grand Slam. The emotions certainly got the better of Konta, who decided not to shake the umpire's hand and momentarily left the court and delayed the trophy ceremony. Before she could return to court, rain fell on court for a time before the players returned to continue the match.
"I knew that Jo was going to be the toughest test this week, so I'm just really glad that I came through that and it was a really high quality match".
Saving the first five break points she faced in the match, Barty looked on course to record her fifth straight sets victory in as many matches this week, only to see Konta make a late push to force a decider.
Barty, who lost to Konta in this event previous year, took just over an hour to complete her routine win on Saturday, breaking Osaka's serve three times and winning 80 percent of points on her own service.