This is the longest unbroken run of medals in the history of the show.
Hillier’s display, on the theme of "Feel good about gardening", featured a series of interlinking gardens containing 3500 plants.
Hillier also won the ‘International Grower of the Year’ award.
Hillier managing director and designer of the exhibit Andrew McIndoe said: "Gardening makes me feel good, but winning Chelsea Gold medals makes me feel fantastic!
"It is the ultimate accolade in the horticultural world, and a great result for a huge team effort. I am extremely proud of the Hillier team. Ricky Dorlay, our veteran Plant Preparer, did a brilliant job in the face of a severe winter and blistering spring temperatures. His 46 years of staging Chelsea stood us in good stead."