Guided by insights from international relations theory, this article investigates China’s adherence to the UN Convention of the Law of the Sea (UNCLOS), asking how Beijing’s attitude towards UNCLOS affects China’s role in Arctic governance and beyond. Examining contested Law of the Sea matters - the dispute over the "nine-dash line" in the South China Sea, the right of innocent passage of warships and the role of international arbitration - it argues that China’s compliance with UNCLOS does matter for understanding how China is perceived as a member of the international community. Further, China’s growing interests and enhanced engagement in the Arctic depend on a strong international legal framework; Arctic governance encapsulates the norms of multilateralism and rule of law. The article concludes by asking whether Chinese experiences from observing and participating in the multilateral governance of the Arctic can serve as an example of successful multilateral cooperation and peaceful conflict solution, of relevance to China also in its nearby maritime regions.