Geoscience diplomacy bridges geoscientific expertise and international policymaking to address complex global challenges. A great example is the Commission on the Limits of the Continental Shelf (CLCS), established under the United Nations Convention on the Law of the Sea (UNCLOS). This Commission integrates geoscientific data and diplomatic negotiation to support coastal states in extending their continental shelves beyond 200 nautical miles. Through the implementation of Article 76, the CLCS facilitates technical assessments, promotes cooperation and provides peaceful mechanisms for resolving maritime boundary disputes. Beyond legal delineation, geoscience diplomacy is important in maritime governance, transboundary water management, energy security, disaster risk reduction, and climate change adaptation. As pressures on shared resources grow, international collaboration in geosciences becomes increasingly important to ensure sustainability and equity. This paper explores how geoscience diplomacy is applied in real cases, such as Nigeria’s successful continental shelf extension submission to the CLCS. It highlights how geoscience-informed diplomacy contributes to peaceful and sustainable governance of maritime and geological resources.