Peel Ports Sheerness has been granted full planning consent by Swale Borough Council for its plans to redevelop the 20-hectare former Thamesteel complex.
The application sought permission for the change of use of the site from B2 industrial use to port related uses (sui generis).
The plans would see the demolition of several buildings on site and the retention of others, including a Grade II listed former military hospital.
They would also see the construction of a new vehicle access and bridge spanning the A249 to the existing port to the west, reconfiguration of a railhead, and other works.
Peel Ports had intended to demolish the hospital building, however it was subsequently listed by heritage watchdog Historic England.
A planning report said that, with the decision to retain the hospital building, "it is reasonable to lift earlier objections to the granting of planning permission".
However, the report added that if "port related use for the building cannot be found (as seems likely to be the case given the consistent feedback from applicant in this respect) then future opportunities for a beneficial use of the building will be more difficult to secure if the building is dominated by port related activities".
Overall, the report said that the plans would result in a "considerable reduction" in the site’s environmental impact, enable the expansion of the Port of Sheerness and preserve local heritage.
Paul Barker, port director at Peel Ports London Medway, which includes Sheerness, said: "The unanimous decision to approve the redevelopment plans at the former Thamesteel site is the first significant milestone in the progression of our 20-year Master Plan for growth at Sheerness.
"Not only will this allow us to breathe new life into a site that has lain derelict for four years, it will also allow us to reconfirm our commitment to the future of the region - creating new jobs and investment opportunities."