The fast-growing group will open its 14th, also in London, in Hackney next month.
It is a busy time for the chain, with a new chief executive, George Dymond, taking over next week. Dymond was previously head of international at Holland & Barrett.
Al Overton, Planet Organic’s buying director, said: “We’re delighted to finally open a store in Hampstead, especially in time for Christmas.
“Few parts of London have stronger communities and we’re anxious to become a meaningful, useful addition to the excellent high street.”
The group says its recent growth is evidence of increasing demand for healthy and sustainable products.