But it was no walk in the park, with less than a rail between the top six coming into the showjumping. Just six of the 29 combinations were clear and inside time.
The four British combinations who finished behind Price put plenty of pressure on her, and while she nudged a couple of rails, everything stayed in place for her to finish on 28.3 penalty points with Laura Collett and Mr Bass second on 29.9, Rosaline Canter on Zenshera third on 29.9 and Kitty King fourth on Ceylor LAN on 32.2.
Price received a standing ovation from the German crowd as she cleared the final fence in the showjumping on her 13-year-old grey.
"We love coming here," Price told the crowd. "It is the highlight of our calendar. This is a special win for Faerie Dianimo."
And an "extra special day" for her UK breeder and co-owner Trisha Rickards.
"It has been a fantastic competition from start to finish," she said. "This mare is spectacular in so many ways. She is tiny – barely 16hh but thinks she is 18hh and bulletproof. It is those qualities that make her quite difficult but equally brilliant, and she showed that brilliance today coming out and jumping like that under pressure."
Faerie Dianimo was Price's Rio Olympic Games horse and in 2015 were second at Luhmuhlen.
"I couldn't be more happy with my two mares," she said, tipping her hat to her Badminton winner Classic Moet as well. "I believe each are such deserving winners (of a four star title)."
She is not the first Price to have won at Luhmuhlen – husband Tim won the aboard Wesko in 2014.
Jesse Campbell, the only other Kiwi left in the field and finished 19th aboard Amsterdam 21 on 71.1. Blyth Tait and Havana retired during the cross country, while Campbell had an unlucky spill on his other horse Cleveland.
The sixth and final four star of the season is at Burghley in England starting on August 31.
New Zealand's four star titles:
9 — Mark Todd, Andrew Nicholson
3 — Blyth Tait
2 — Nick Larkin, Jonelle Price
1 — Caroline Powell, Jock Paget, Tim Price, Matthew Grayling, Clarke Johnstone.
Total: 30 (Burghley 13, Badminton 7, Adelaide 3, Kentucky 3, Luhmuhlen 3, Pau 1)