The court in Annecy also heard Mr Veyrat ordered a large portion of protected wetlands to be dried up.
He was one of five chefs picked to cook for world leaders at the Paris talks.
He was ordered by the court to pay a fine of €100,000 (£73,000; $108,000) and to restore the wetlands within three months.
Mr Veyrat, who has twice obtained three Michelin stars, told the court he acted with the best of intentions, as he built an educational centre for children.
He also built a botanical garden, beehives and greenhouses at the site, near the town of Manigod in the Haute-Savoie region.
After the hearing, Mr Veyrat apologised, saying: " I am not above the law. Anyone can make a mistake, even me."
At the end of the talks in Paris, countries agreed to a firm goal of keeping temperature rises well below 2C, and will strive for 1.5C.
But one study claims that deforestation is the second-largest man-made contributor of C02 into the atmosphere, which is seen as a major contributory factor to temperature rises.
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