The Chilean holed a seven-foot eagle putt across the 18th green on the second extra hole as rain began to fall to win the Stonehaven Cup at The Australian Golf Club in Sydney on Sunday.
Niemann, who began the final day four shots adrift of overnight co-leader Hoshino, posted a five-under-par 66 to set the clubhouse target at 14 under which was later matched by the Japanese as he carded a one under 70.
Both players made birdie on the first play-off hole at the 18th, with Hoshino getting up an down from a greenside bunker before Niemann saw an eagle putt from five feet slide past.
Despite Hoshino again doing well to make a birdie after going bunker-bunker for the second time in succession, Niemann sealed victory after another fine approach shot.
The win for Niemann is his first on the DP World Tour and sees him become just the second Chilean to do so after Felipe Aguilar.
“It was a nice day. These last two playoff holes showed how I have been playing the last few weeks here in Australia,” said Niemann.
“My putting hasn’t been the best, but I’ve been working hard on it and it was nice to make that last putt.
“I always practise those three, four, five-feet ones and know that one of those will be to win a tournament. It’s amazing.”
Australian fan favourite Min Woo Lee finished solo third two shots back after a 72 as he missed out on becoming just the seventh player to win the Australian PGA Championship and Australian Open in the same year.
Adam Scott finished a shot further back in a tie for fourth at 11 under alongside Grant Forrest and Laurie Canter after the Masters winner carded a closing 68.
With Lee already qualified for The 152nd Open at Royal Troon next year, Scott joined Niemann and Hoshino in securing the third and final qualifying spot in the starting field due to his higher standing on the Official World Golf Ranking than British pair Forrest and Canter.
After the second of back-to-back co-sanctioned events with the PGA Tour of Australasia on the DP World Tour’s Opening Swing, Lee sits first on the Race to Dubai Rankings in partnership with Rolex with Hoshino just behind him after his second runner-up finish in as many weeks.
In the women’s event, South Africa’s Ashleigh Buhai finished a shot ahead of home favourite Minjee Lee to successfully defend her title, while Lachlan Wood won the G4D Tour’s season-opening ISPS HANDA Australian All Abilities Championship on Saturday.
