"To win the New Zealand Open, that's got so many great names on the trophy, it's a real step forward for me."
It took a 1.2 metre birdie putt to seal the win, earning Griffin a $180,000 share of the $1 million prize purse.
"That was the most nervous I've been," he said. "I did a lot of deep breathing on the green and it was a nice putt, just right edge and I got it to start off on a nice line and it just hung on that left edge."
Tanihara carded a two under par 70 to be 19 under to finish on 268, but will have nightmares tonight after faltering on the 18th.
From the tee he drove into the rough, before the second shot found the bunker. He managed to chip out safely, but missed a 4.5 metre putt which robbed him of a playoff chance.
"When it went in the bunker I thought it would be ok," he said via a translator.
"I wasn't particularly worried and it wasn't a shock. However, the last put I had it thought it was going to go and I just came up a bit too short which was a shame."
Griffin's win continues a five-year run of Australian winners, following on from last year's champion Jordan Zunic, and Dimitri Papadatos (2014), Jake Higginbottom (2012) and Brad Kennedy (2011).
Hendry pocketed $58,000 after carding a seven under par 65 to finish 14 under on 273, but rued a slow start with two par 71 scores on the opening days.
"There are a lot of mistakes that I'm lamenting from Thursday and Friday," said Hendry.
"Thursday's round promised a lot early and was a little bit weak coming in, and then the beginning of Friday's round was really poor too.
"Those 15 holes through the middle probably cost me a real good chance for the tournament unfortunately."
Alker, who occupied third place at the start of the day, had to settle for sixth, having carded a two under par 70 to be 12 under on 275.
The Hamilton-born 44-year-old opened with a birdie before two bogeys on the second and fourth holes. He looked to have found his rhythm through the back nine with a trio of birdies on the 10th, 11th and 13th but lost his mojo through the last five holes.