Home Postcode finder WA Rossmore Rossmore postcode WA Rossmore is a locality in Western Australia covered by postcode 6401. Postcode 6401 State or territory Western Australia (WA) Region Wa Subs 1 G Flds Add a free Rossmore business listing Be the first listing in Rossmore Common questionsWhat is the postcode for Rossmore?Rossmore, WA has the postcode 6401.What state is Rossmore in?Rossmore is in Western Australia (WA).Does postcode 6401 cover more than one suburb?Yes. Postcode 6401 covers 18 localities, so the postcode alone does not identify Rossmore. Browse other postcodes in Western Australia, or widen the search to every Australian postcode.