In a statement, Optus said the mmWave sites used the 800Mhz bandwidth of the 26Ghz spectrum, which meant much higher speeds though the telco will have to put in place more towers due to the shorter transmission.
The new mmWave sites are in Kings Cross, Surry Hills, North Ryde and Optus Sydney Campus (all Sydney), Huntingdale (Melbourne) and Strathpine (Brisbane).
Earlier this week, the telco opened a 5G lab in Perth in association with Curtin University to test out 5G use cases.
"The demand from our customers for 5G capable devices has surged in recent months, with eight out of 10 handsets that we sell today now [being] 5G-enabled. One million 5G devices is just the beginning for us and as we grow our 5G network and launch new capabilities we expect our 5G customer base to grow in parallel.
"Customers want and expect the latest tech when it comes to their network and at Optus we are committed to delivering this, which is why today we have also switched on our first six mmWave sites."
Lambo Kanagaratnam, managing director, Network, Optus said, "We've been testing mmWave for many months, harnessing and pushing its capabilities so that once commercial devices enter the market our customers will truly be able to benefit from the capacity and speeds that this incredible technology delivers.
"In fact, mmWave is set to blow current mobile and home Internet speeds out of the water, with the potential for multi-gigabit speeds which is much faster than what Australians are used to getting today."
The company said mmWave technology would be a gamechanger for high simultaneous data consumption locations like sports stadiums and special event locations such as Sydney Harbour during the New Year's Eve fireworks.
"mmWave will also pave the way for a host of new solutions across enterprise and government, with its blazing fast gigabit speeds and high-volume capacity expected to drive change in the way companies automate and innovate within their business," the company said.
Optus has 1200 5G sites, including the six mmWave enabled sites.