The Court said that unless Nestle proved that UK consumers identified the chocolate by its shape alone, it couldn't trademark the signature design.
Nestle's arch-rival Cadbury had fought the Swiss cocoa giant's attempts to register the design.
Sally Britton, intellectual property lawyer at Mishcon de Reya, told the BBC that Nestle was likely to continue its efforts, "even if, as now appears likely, the English court decides that the KitKat shape should not be registered as a trade mark".
But how easy is it to identify a chocolate bar from its shape? Take our quiz to test your sweet-toothed knowledge...