This chapter examines the dynamics of soft power diplomacy within the context of the BRICS+ 5 bloc and the extent to which it can leverage peace, security, and stability—and, hence, sustainable development. The role of South Africa in the context of intensifying geopolitical competition is the focal point of this chapter. Soft power, as conceptualised by Joseph Nye, plays a crucial role in shaping international relations, fostering cooperation, and achieving peace and security. Within the BRICS+ 5 framework, South Africa’s soft power strategies are analysed in light of its unique geopolitical positioning and domestic socio-political landscape. Soft power tools such as cultural diplomacy, economic cooperation, and multilateral engagement have the potential to enhance South Africa’s global influence and address regional and international challenges to peace and security. Furthermore, the chapter explores the implications of escalating geopolitical rivalries, particularly between major powers, on South Africa’s diplomatic manoeuvrability and security interests. This study relies on secondary data, research articles, books, and websites. Descriptive statistics and Composite Index (CI) were used to obtain the empirical outcome. We argue that while South Africa’s soft power initiatives have contributed positively to regional stability, aiding in the search for global peace and sustainable development, mounting geopolitical tensions pose significant challenges. These challenges include potential alignment pressures, economic dependencies, and risks to South Africa’s autonomy in foreign policy decision-making in a unipolar world. By examining the interplay between soft power, geopolitical competition, and South Africa’s national interests, this chapter provides insights into the evolving dynamics of global governance and the imperative for adaptive diplomatic strategies in an increasingly multipolar world, and harnessing internal peace, stability and sustainable development.