The Western Australian Government spends roughly A$300m a year on IT and is attempting to reduce costs through the consumption-based contract.
As a part of a three member panel of preferred suppliers, Datacom will have the right along with NEC and Atos to bid on all new work as it arrives.
"The appointment of Datacom as one of three suppliers of ICT infrastructure to the Western Australian Government marks the beginning of an exciting new digital era for the public sector," Western Australia Government Innovation Minister Bill Marmion said.
"The new arrangements will modernise technology across government and provide the technical platform for the state's ICT Strategy Digital WA. We look forward to working with Datacom, and the two other suppliers, over the term of this contract."
Datacom chief executive Jonathan Ladd said: "We're proud to have been awarded this work after going through such an intensive, competitive tender process. This is an innovative, forward-thinking project that will transform how the Western Australian Government provides services to its citizens.
"We look forward to working with the Government to successfully transition its agencies to these new platforms, providing the world-class infrastructure and support to match the Government's vision for truly 21st century governance - flexible, efficient and cost-effective."