He scooped the Best Planting award and also a gold medal for his garden, Finding Inner Peace.
His garden this year explores the concepts of inner peace and sanctuary, with a maze-like space which is visually confusing at first. It explores the idea through a physical garden of how difficult it is find inner peace but that if people work through the obstacles life throws in their paths it can be achieved.
Gardening World Cup judge Andrew Fisher-Tomlin said: "Paul won for a very intelligent design that played with views within and around the space, masterly combinations of plants and a faultless construction that fully realised the theme of this year's show which is 'floral paradise'."
The Gardening World Cup runs until 3 November at the Huis Ten Bosch Park in Nagasaki. Kate Hillier, Dougal Philip and master architect of Huis Ten Bosch Sirou Wakui were the other judges.
Hervey-Brookes won a bronze medal for his BrandAlley show garden at this year's RHS Chelsea Flower Show and a gold and the Best Planting award at the 2013 Gardening World Cup.