The six-month heavy vehicle trial comes as the national mail carrier revealed plans to phase out petrol-powered motorcycles within three years in its latest commitment to green transport.
The carrier has already added more than 4600 electric vehicles to its network, helping it to cut more than 7000 tonnes of carbon emissions over three years.
Australia Post sustainability executive general manager Tanny Mangos said the new commitments were designed to prove more businesses could transition to electric transport.
"As one of Australia's largest employers and an iconic Australian institution, we take our responsibility to drive change for a safer and more stable future seriously," she said.
"The electrification of our vehicle fleet is critical to reducing our emissions and key to achieving net-zero by 2050."
As part of the new trial, a Volvo FL truck has been deployed at Australia Post's Redbank Plains Distribution Centre, on Brisbane's outskirts.
The truck is capable of moving a payload of 5500 kilograms for 300 kilometres on a single charge, a step up from the corporation's existing delivery vehicles designed for last-mile deliveries.
"We're now turning our focus to electrification of our medium and large vehicles," Ms Mangos said.
"We have such a complex national ecosystem and there are quite a few barriers to the electrification of truck fleets but we remain committed to it."
Volvo Group e-mobility manager Tim Camilleri said it was "rewarding" to see electric trucks finally on Australian roads.
"These vehicles are proving themselves day in and day out around the globe," he said.
The electric truck will join 4635 electric vehicles in the Australia Post network, including three light-duty eCanter trucks used in Melbourne depots, 1507 electric bikes, and 3125 electric delivery vehicles (EDVs).
While the electric vehicles were initially deployed to cut emissions, Ms Mangos said they had also cut costs and proved safer for riders.
"We are now working to phase out (petrol) motorbikes," she said.
"It will be important that those motorbikes are replaced with safer modes of transport and we've identified EDVs as safer."
Cutting emissions in other parts of the network would be harder, she said, and Australia Post had partnered with Qantas on sustainable aviation fuel trials.
The company was also investigating "bespoke" electric vehicles to deal with more challenging terrain and unpaved roads in regional and rural settings.
"It's one thing to have a vehicle that's driving through metro centres but our reach is beyond metro and Australia is a vast, vast land with differing terrain," she said.
Other electric trucks deployed in Australia include a trial of 60 electric delivery vehicles by courier firm Team Global Express, formerly known as Toll, in its Western Sydney Hub.
The $44.3 million project to create a Depot of the Future was part-funded by the Australian Renewable Energy Agency.
