The Medway towns' campaign for city status during the Queen's Jubilee Year in 2012 has received the backing of Kent County Council.
The campaign brings together the towns of Rochester, Strood, Chatham, Gillingham and Rainham.
Paul Carter, the leader of the Conservative-controlled county council, said he was behind the bid.
Medway made two unsuccessful bids in 2000 and 2002. On the last occasion it lost out to Brighton and Hove.
Mr Carter said: "Medway's status will be enhanced as a place to visit, live and do business with.
"It will also set it apart from many other authorities, by making it even more of a 'place' rather than just a series of towns."
Councillor Rodney Chambers, the Conservative leader of Medway Council, said the area had the "thriving atmosphere and forward thinking attitude of a city".
Rival bids are set to include Milton Keynes in Buckinghamshire and Reading in Berkshire.