NEXTDC's C1 data centre in Canberra is the company's third - it already operates centres in Brisbane and Melbourne.
The first customers have moved into C1, the company announced today.
The facility is housed in a building that was originally constructed for the Federal Government, in consultation with ASIO to meet the ATO's requirements.
NEXTDC CEO Craig Scroggie said C1 has been designed to very high standards to meet a range of physical security specifications.
Other features include two on-site substations with separate feeds, water-cooled chillers, and plans to adopt free air cooling as part of future upgrades.
Fibre connections to C1 are provided by Optus, Telstra, Vocus, NextGen Networks, PIPE Networks and AAPT.
Company officials did not disclose the identity of the first customers, only that "C1 will provide much needed data centre capacity to various Government agencies and service providers"