The champion was feeling relieved after the tense play-off.
"It was nerve-wracking, especially after my first drive which went way left. I hung in there. He just missed his chance to win and then I finally got home.
"[On the final hole of the play-off] I slightly chunked a six iron and then had a putt that I knew really well, I've had that putt a few times before and I was pretty confident I'd make it.
"It's special to win especially with a crowd around 18 like that."
Klein, of German heritage, had a clinical game plan for the final round.
"I wanted to minimise mistakes, hit fairways and greens and take my chances, I was bogey-free, so it worked."
The shortest hitter of the three players by some distance played his own game and carded a four-under 68 to keep Fox (67) and Pender (68) at bay for most of the afternoon.
He held a two-shot lead over Fox and Pender with four holes to play. But both of the challenging players made birdie on the 15th and 16th to have scores in the lead group tied on 13-under with two holes remaining.
Pender bogeyed the penultimate hole to trail by one down the last. Fox had the best chance to win the tournament in regulation with an eagle putt from 2.5m but it came up short so the pair were tied on 14-under after 72 holes of stroke play.
Fox had another good chance to win on the second playoff hole but his putt sat on the lip.
The former New Zealand amateur rep hit his third tee shot down 18 way left and Klein made no mistake with his birdie chance to seal the win.
He had headed to the New Plymouth event on the back of a nine-under 63 to win the Hawera Pro-Am and said the hot scoring had come down to a putter change.
"It has definitely been a good change. I putted a lot better at Hawera and I carried that on to here.
"It is a big key to my game."
Klein, whose plans to study as a helicopter pilot have been put on hold with his recent success as a tour pro, had enjoyed the trip to the Taranaki region. He said his improvement was down to rededicating himself to the pro game and "playing smart".
Klein claimed the lion's share of the $40,000 prize purse on offer at the New Plymouth Golf Club.
Meantime, Fox was philosophical about missing his first Charles Tour title as his dream start to his rookie year as a pro continued.
"This is the best I have done here. David played really solidly today.
"I gave myself a couple of chances both in regulation and in the play-off and I missed the putt and he made his. I am obviously pretty disappointed to have missed my chances to win but all in all it was a pretty good day."
Local legend Grant Moorhead finished alone in fourth place, while reigning Carrus Tauranga Open champion Jim Cusdin and 2011 Taranaki Open champion Josh Carmichael shared fifth.
Royal Auckland golfer Fraser Wilkin claimed the amateur title from Craig Hamilton (Omanu) by five shots.
Pre-tournament favourite Mark Brown bounced back in the final round with a three-under 69 to climb to tied 10th.
Meantime, in the women's division defending champion Emily Perry won by 13 shots after a two-over-par 74 in the final round.
She was delighted to win another title and get the ideal confidence boost before the Queen Sirikit Cup in two weeks' time.
"It is great to win three titles in a row," said the 21-year-old from the Lochiel Golf Club, near Hamilton, who has won the North Island Strokeplay and New Zealand Strokeplay titles in 2012.
"Hopefully we can make it four in a row by winning the Queen Sirikit Cup in Singapore. I want to congratulate Tyla [Kingi] and Emma [Clayton] for how they played this week."
Perry held a 10-shot lead heading into the final round but was focused on setting her own standards.
"It was comfortable. I played really well on the front nine and then I had a few loose shots on the back nine but I tried to keep the pressure on myself and play the golf I wanted to.
"I am really happy overall with my form heading into this week, there are a few things to work on but I am happy and confident.
"It's been really hot this week and I think I'll go for a run in my thermals to get ready for the heat in Singapore.
"We have a great team and we're going to be ready for it."