Home Postcode finder SA Seddon Seddon postcode SA Seddon is a locality in South Australia covered by postcode 5223. Postcode 5223 State or territory South Australia (SA) Region Sa Subs Near 2 Add a free Seddon business listing More business listings in Seddon Businesses in SeddonEcopia Retreat563B Gregors Road, Seddon SA, Australia · 0414 751 733 Common questionsWhat is the postcode for Seddon?Seddon, SA has the postcode 5223.What state is Seddon in?Seddon is in South Australia (SA).Does postcode 5223 cover more than one suburb?Yes. Postcode 5223 covers 30 localities, so the postcode alone does not identify Seddon. Browse other postcodes in South Australia, or widen the search to every Australian postcode.