Diplomacy has been an essential tool of any country's foreign policy in the international system. Through diplomacy, nations conduct their international affairs; however, with the changing times, the nature of diplomacy has been widening, and health diplomacy has been one of the significant tools of any country to establish cordial relations with nations worldwide. To put this in place, it has emerged as one of the crucial components of ``soft power.'' Moreover, it is a vital conduit for international cooperation in addressing global health challenges, particularly advancing Sustainable Development Goal 3 (SDG 3)---ensuring healthy lives and promoting well-being for all. This chapter explores the intersection of health diplomacy, particularly India's involvement, and the crucial role of mental health within SDG 3. It explains health diplomacy as a form of soft power and its importance in governing global health.