Pilbara Iron is a wholly owned subsidiary of the multinational Rio Tinto Group, that manages assets for Hamersley Iron Pty Ltd, a wholly owned subsidiary of Rio Tinto, and Robe River Iron Associates, an unincorporated joint venture between Rio and three Japanese steel companies Mitsui Iron Ore Development P/L (33%), Nippon Steel Australia P/L (10.5%) and Sumitomo Metal Australia P/L (3.5%).

The Hamersley & Robe River railway, majority-owned by Rio Tinto, and operated by its subsidiary Pilbara Iron, is a private rail network in the Pilbara region of Western Australia for the purpose of carrying iron ore. The network is larger than any other Australian heavy freight rail network in private ownership. The total length of its track is about 1,700 km (1,056 mi).