Security cooperation between South Korea and Australia has increased in recent years. What has been driving this increasingly enhanced security cooperation between the two states, which are about 7,500 km apart from each other? This article approaches the question from the angle of minilateral security cooperation, which has been growing in the Asia–Pacific. It is relatively easier to build minilateral security cooperation upon an existing bilateral alliance relationship or strategic partnership. This practice has been led in the Asia–Pacific by the United States, which has been maintaining the so‐called hub‐and‐spoke alliance network and expanding its security interactions with non‐allied states. It is in this vein that this article locates security cooperation between the two US allies, South Korea and Australia, in the larger context of the US‐led minilateral security network in the Asia–Pacific. After observing that South Korea and Australia have been enhancing their security cooperation, the article looks into those states' stances on the US attempt to facilitate security linkage among its Asia–Pacific allies. Then, the article examines the (un)desirability and (im)possibility of developing trilateral or quadrilateral security cooperation among South Korea, Australia, the United States and Japan. It claims that the expectation of a US‐led minilateral security cooperation being developed is a key reason for the recent enhancement of bilateral security cooperation between South Korea and Australia. Lastly, it discusses some issues to consider in further promoting South Korea–Australia security cooperation in the context of US‐led minilateral security cooperation.