The charter, which will be launched during climate talks in Poland, will call for companies to work together to create affordable low-carbon production methods. Currently, the fashion industry is one of the most damaging to the environment.
According to reports, some major fast fashion brands have signed up to the charter, though it has not yet been revealed who they are.
"We really don't have long now, to change things," McCartney told The Guardian. "But I honestly believe it's doable - I couldn’t do what I do if I didn’t believe that.
"There is so much guilt and fear attached to talking about sustainability and that's not helpful.
"What is essential is for the big players in the industry to come along with me, because that changes the price point."
McCartney has hit the headlines in recent times, thanks to her use and support of low-impact innovative fabrics.
Last year she teamed up Silicon Valley biotech company Bolt Threads to create yeast-based vegan silk. She also joined forces with Parley for the Oceans to use recycled ocean debris in her designs.
As a result, she was awarded a Special Recognition Award for Innovation by the British Fashion Council at 2017's Fashion Awards, for championing sustainability and animal rights in her work.