The chocolate giant has been battling its Swiss rival Nestlé for the last four years over the use of the purple, which has appeared in Cadbury's packaging for almost 100 years.
Last December a court ruling gave Cadbury exclusive rights to the hue, despite Nestlé's claims that a colour could not be used as a trademark.
Now Britain's High Court has overturned Nestlé's appeal, ruling that Pantone 2685C purple is "distinctive of Cadbury for milk chocolate."
Pantone's colour system is used by printers and designers around the world to standardise and accurately match colours. Cadbury uses 2685C purple in its logo and its most recognisable packaging, such as Dairy Milk and Twirl bars.