Arms were granted to the Synod of the Diocese by the Royal College of Arms on 29 March 1982.
The heraldic description of the Arms includes a bendy wavy Azure and Argent Maltese Cross on a Chief Argent Cross between four Estoiles Gules.
The chief (top of the Arms) bearing the red cross and the four wavy stars is taken from the Arms of the Diocese of Adelaide.
The base (bottom of the Arms) depicts the waves and sand bars of the River Murray.
The Maltese Cross (or the cross of St John the Baptist) signifies the patron Saint of the Cathedral Church.