The decision is an important symbolic victory for environmentalists who said the company's "Fly Responsibly" campaign was misleading given that all aviation is an important source of greenhouse gas emissions.
"A number of advertisements made by KLM in the past were misleading and therefore illegal," the court said in a summary of the judge's written decision.
However the company will not be forced to issue any rectification, and it may continue to advertise to customers. In the future, the firm must be "honest and concrete" about environmental claims, the court said.
(Reporting by Toby Sterling; Editing by Jan Harvey)
By Toby Sterling and Joanna Plucinska
