Eight hundred jobs are at risk after the owners of Chatham Docks said it would be financially unsustainable to maintain it as a port beyond 2025.
Peel L&P said it was supporting other uses for the site, including "much needed housing on brownfield land".
Spokesman Paul Chappels said the company had been in talks with tenants about relocating to alternative sites.
Several have already formed an association to try to protect the long-term future of the commercial port.
The Association of Chatham Docks Commercial Operators (ACDCO) consists of 10 businesses whose aim is to stop plans to extend the Chatham Waters development to include the docks.
The scheme, which was approved by Medway Council in 2013, includes office space, education facilities, flats, townhouses and a superstore.
Peter Alexander, director of Steel Fuel, said: "Chatham Docks is a thriving commercial port and manufacturing site.
"The businesses here directly support 800 full-time skilled jobs and more than 16 apprentices.
"Under Medway Council's new Local Plan all of this is going to be torn apart. Feelings are running high."
Mr Chappels said: "We've been in discussions with existing occupiers about our plans for a number of years and will continue to work with them to find alternative locations such as the port facility in Sheerness.
"We will continue to manage the estate in accordance with the lease terms that expire in 2025."
The port - not to be confused with Chatham Historic Dockyard or Chatham Maritime - operates as a 75-acre commercial port and manufacturing hub.