Dean Dalla Valle and Susan Lloyd-Hurwitz, the latest appointments, will join Rio's board on June 1, the miner said.
Valle was previously chief commercial officer of BHP Group. and CEO of Australian rail freight operator, Pacific National.
Earlier this month, he was appointed as chair of hydrogen electrolyser technology company, Hysata.
Lloyd-Hurwitz served as the chief executive officer and managing director of ASX-listed property firm Mirvac Group for a decade before stepping down recently.
Most of the directors on Rio's board are experienced in finance, capital markets, law and oil and gas.
Chairman Dominic Barton said last October that Rio needed more members with mining and renewable energy experience and with a more diverse geographical background.
"Dean and Susan will deepen the board's capabilities and experience in key areas we had identified that needed strengthening," Barton said in a statement.
(Reporting by Harish Sridharan in Bengaluru; Editing by Saumyadeb Chakrabarty and Savio D'Souza)