The 18-year-old's three‑dart average of 115 is officially the highest ever recorded in a World Series event played in New Zealand.
Littler wrapped up a second consecutive World Series title in as many weeks, having already won the Australian Darts Masters just one week earlier – a sequence often referred to as the 'Oceanic double'.
In the semi‑final, he dismantled Gerwyn Price 7‑2, averaging 108.8 while landing five 180s and a 140 checkout, having beaten Mike De Decker 6-2 in his first match of the day.
In that game, Littler still averaged 95.6, hit over‑100s fourteen times, recorded eight 140+ visits, and converted six of 13 checkout attempts with a top finish of 80.
In the final, Littler seized control early. He surged to a 3‑0 lead, executed a precise 83 checkout, then followed with legs of just 13 and 11 darts to establish a 6‑2 advantage.
"It felt very much the same as last week," Littler told the PDC after lifting the trophy, having won his last 13 matches in all competitions.
"I had a shaky start in my opening game, but once you come into Finals Night, you know you have to switch it on, and that's what I did again tonight.
"I felt unbeatable up there. The crowd were brilliant and the venue was incredible – it felt like a Premier League night, and I'm very happy to lift another title.
"I'm playing very well at the moment, I'm enjoying my darts and hopefully I can keep this winning streak going."
Humphries responded briefly with 13 and 11‑dart legs, but Littler clinched the match with successive 11‑darters.
Humphries rebounded from his Australian disappointment and reached the final after a semi‑final win over Chris Dobey, where he averaged 102 and landed seven 180s.
In the final, he averaged 102 as well, but was frank in defeat: "I played pretty well today, but when you run into a 115 average, there's not much you can do.
"The better player won for sure. When Luke's on it, he's untouchable."
Earlier in the night, Dobey edged Stephen Bunting 6‑3, averaging 110.
Gerwyn Price survived a last‑leg decider against Josh Rock to make the quarters.
This triumph adds to an already overflowing 2025 trophy cabinet for Littler, which includes the World Championship, World Matchplay, UK Open and now two back‑to‑back World Series titles.
He now heads to Amsterdam for the Jack's World Series of Darts Finals on September 12th in pursuit of retaining his title.
Stephen Bunting is set to arrive as the top seed, having won World Series events in both Bahrain and Copenhagen earlier this season.