Heirisson Island is an island in the Swan River in Western Australia at the eastern end of Perth Water, between the suburbs of East Perth and Victoria Park. It occupies an area of 285,600 m2 (3,074,000 sq ft), and is connected to the two foreshores by The Causeway. The next upstream island is Kuljak Island, then Ron Courtney Island, with no islands in the Swan River downstream between Heirisson Island and the Indian Ocean.
Before development, there were several small islands, surrounded by mudflats. The Noongar name for the area is Matagarup (meaning "leg deep"), which has been retained for the single island after reclamation.
Over the years, dredging and reclamation has created a single island, which is now a landscaped nature reserve, with a 2 km (1.2 mi) walking path.
In 1998, five female western grey kangaroos were introduced onto the island, followed by a female with a male joey in 2000.