Under the contract Babylon will provide offsite repair services for pumps and generators across multiple Rio sites.
The contract is for a firm three-year period, with an option to extend work for a further two years.
The value of the contract was not made public, however Babylon said it was "material" and noted it had received nearly half a million dollars' worth of work over the past year or so.
"Babylon's board is grateful for the confidence Rio Tinto has placed in the company and looks forward to continuing a strong and positive working relationship with Rio," Babylon said.
Contracted work has already begun.
Over the past 15 months, Babylon has received $450,000 worth of revenue from Rio Tinto contracts.
The latest contract win from Rio Tinto follows an award from Alcoa just days earlier.
Alcoa contracted Babylon to provide maintenance services on-site for a further 36 months.
Previous work from Alcoa over the past year amounted to more than $2.8 million.
Babylon had 24% growth in revenue over the past 12 months.
The company was founded in 2017, and since listing in January 2018, has grown from a $1.6 million company to record revenue of $21.3 million last year.
It expects significant growth this financial year too and hopes to reach a target of $100 million worth of revenue within the next five years.