The mining major has defined some 503mln tonnes of inferred resources at a grade of 0.45% copper equivalent, including a higher-grade component comprising 188mln tonnes at 0.68%.
Work to date suggests there is sufficient resources for a relatively shallow open-pit mine, the FTSE 100-listed group said in a statement. First product is presently slated in 2023, with Rio working alongside the local Nyangumarta and Martu traditional owners.
Rio also noted the discovery of a new zone of gold dominant mineralisation around 2 kilometres east of Winu, plus a number of other positive drill results in close proximity to the maiden Winu Resource.
It said there is potential for a development with multiple ore bodies within one system.
"We are very pleased with the progress at Winu as it adds a further option to our strong copper portfolio in a country that is home to many of Rio Tinto's world-class operations," Arnaud Soirat, Rio Tinto chief executive of copper and diamonds said in a statement.
Stephen McIntosh, group executive of Growth & Innovation and HSE added: "We're taking a more agile and innovative approach at Winu, and are working on the studies for a small-scale, start-up operation focused on Winu's higher-grade core as we take another step towards commercialising this deposit.
“We are also assessing options for future expansion in the Paterson region given the extent of mineralisation identified to date and our large land package."