Home Postcode finder WA Oldbury Oldbury postcode WA Oldbury is a locality in Western Australia covered by postcode 6121. Postcode 6121 State or territory Western Australia (WA) Region North West Suburbs Add a free Oldbury business listing Be the first listing in Oldbury Common questionsWhat is the postcode for Oldbury?Oldbury, WA has the postcode 6121.What state is Oldbury in?Oldbury is in Western Australia (WA).Does postcode 6121 cover more than one suburb?Yes. Postcode 6121 covers 2 localities, so the postcode alone does not identify Oldbury. Browse other postcodes in Western Australia, or widen the search to every Australian postcode.