Located around 50 kilometres west of Rio Tinto's Pannawonica operation, the new open-cut iron ore mine will have an initial production of 20 million tonnes per annum, before increasing to 25 million tonnes by 2011.
Rio Tinto holds a 53% share in the project, valued at US$478 million.
Construction of the Robe River Joint Venture mine and rail extension first got under way in November 2007.
According to Rio Tinto, the mine will employ up to 220 people, drawn progressively from a combination of the existing workforce at its Mesa J operation and new employees.
The new iron ore mine will be a boon for local people and surrounding economies, Rio Tinto chief executive iron ore and Australia Sam Walsh said.
"This is a great day for Rio Tinto, and for the Pilbara," he said.
"Mining in the Robe Valley has been an integral part of the north-west economy for decades, and this new mine will ensure it continues to contribute to the benefit of the wider community.
"I am especially pleased to note that construction has been completed on time and inside budget.
"This effort has been echoed by the commencement of pre-strip work at the Western Turner Syncline development (near Rio's Tom Price mine) the same week, making it a dual milestone for Rio Tinto in the Pilbara."
Total high-grade reserves across the Mesa A / Warramboo deposits are estimated at 249 million tonnes, with a total mine life of up to 11 years.
Rio Tinto iron ore believes the mine will sustain production of the high-demand Robe Valley pisolite ore at 32 million tonnes per annum as production from its nearby Mesa J deposit decreases.
The first full-length train left the mine on the Friday of its first week of operation, following the newly finished 49-kilometre rail extension to connect to the Deepdale railway running from Pannawonica to the Cape Lambert port.
