South Korea plans to take part in Exercise Talisman Sabre next month, according to Yonhap news agency.
Seoul will send a destroyer to participate in the exercise.
"We've decided to join the exercise for the first time this year with a goal to improve our capabilities of conducting combined operations," a military official said.
Other participating nations include NZ, Canada, the UK and Japan, with France, India and Indonesia observing.
Talisman Sabre tests the ADF and US forces' in 'planning and conducting Combined and Joint Task Force operations, and aims to improve the combat readiness and interoperability between Australian and US forces,' according to Defence.
Talisman Sabre 21 is the ninth iteration of the exercise and consists of a Field Training Exercise incorporating force preparation (logistic) activities, amphibious landings, ground force manoeuvre, urban operations, air combat and maritime operations.