Simon had been Optus Business' acting managing director since the departure of Peter Kaliaropoulos ealier this year. Prior to this, he was director of the telco's Integrated Business Solutions division.
"John and the Optus Business team have continued to win key corporate and government customers despite fierce competition," Optus chief executive Paul O'Sullivan said.
"Some major wins have included NSW Health, Toll, Mayne and the Victorian Government's TPAMS project while also retaining existing business in major accounts such as ING, IBM, St George and Suncorp.
"He played a key role in transitioning our Business Mobile division into Optus Business following the company's realignment into Customer Facing Units and was instrumental in our acquisition of Uecomm and our pending acquisition of Alphawest," O'Sullivan added.
Simon was selected from a list of internal and external candidates for the position, according to Optus.
He has been with the carrier for four years. Prior to joining Optus, Simon was chief executive officer, Australia & New Zealand for Worldxchange Communications.