Transport Secretary Louise Haigh granted development consent paving the way for contractor Dragados to start work on the £125m eastern Ro-Ro Terminal plan next year.
Works are set to cover at least 46 acres. The new roll-on/roll-off facility comprising a new jetty with three berths, improved hardstanding, terminal buildings and an internal side bridge to cross over existing port infrastructure.
It will allow a further six ships a day to use the port.