The actress and the director both live close to the exclusive area of Primrose Hill in north London, and they are backing a drive to stop cosmetics chain Space Nk from launching a new store in the district.
Many local residents oppose plans to open a Primrose Hill branch of the store, fearing it will be a blow to small, independent businesses, and Frost and Taylor-Johnson have joined in by signing a petition.
Frost, who lives locally with her children from her marriage to Jude Law, tells the Ham & High local newspaper, "Primrose Hill Village is unique and special because of the local, independent shops. If one chain arrives, others will follow. We need to protect these businesses and not let it turn into another big-chained high street."
Taylor-Johnson adds, "Primrose Hill is full of small businesses that give the area such strong character."
A spokeswoman for Space Nk says, "Space Nk is very much a neighbourhood retailer and passionate pioneer of British business on the high street... In order to maintain a busy, healthy high street that delivers to the local community, it needs to be a place which adapts and changes while retaining its individuality and integrity. However, at this time nothing has been confirmed with regards to us opening a store on Primrose Hill."