The bridge at Michaelstone-y-Fedw will be closed for essential maintenance between Wednesday 16th and Wednesday 23rd December.
Caerphilly county borough council manages the structure, which crosses the border between the Caerphilly and Newport local authority areas.
Motorists are urged to avoid the area and use alternative routes during the closure.
The contractor, Edwards Diving Services Ltd, is erecting signs informing members of the public about the works.
