The company claimed in a statement that the renewal was "a strong endorsement of the shared products and sales team capabilities of the merged businesses".
The renewal means that annual recurring revenue from Defence is $950,000.
archTIS Global chief operating officer and US president Kurt Mueffelmann said: "I am delighted that the Australian Department of Defence has renewed its subscription of NC Protect to safeguard sensitive information.
"Defence is a joint customer of Nucleus Cyber and archTIS. archTIS and Nucleus Cyber attributed based access control technology platforms and shared customer base validate this modern approach to protecting highly sensitive data across the world's most classified networks. We look forward to the continued expansion of the Defence relationship."
archTIS acquired Nucleus Cyber in December last year.
archTIS managing director Daniel Lai said: "This renewal demonstrates the strategic value of the Nucleus Cyber acquisition. It provides our customers with a range of policy enforcement products to secure and share their information assets.
"The merger now means archTIS can provide award-winning products to secure our clients' Microsoft business applications. The Defence renewal validates the quality and uniqueness of NC Protect.
"This renewal and our recent Kojensi sales strongly position archTIS as a key provider of information security products to the Australian Department of Defence.
"This is an exciting time for archTIS as it continues to successfully execute our strategy to become the global leader of policy enforcement in the protection and sharing of sensitive and classified information."