Mountain tourism in Romania developed relatively late, beginning in the late nineteenth century and continuing into the early twentieth century, with many fluctuations. Recently, marketing has emerged as a catalyst for sustainable growth in this sector through targeted policies and strategies. This chapter reviews the marketing approaches specialists and practitioners employ in mountain tourism. It includes three case studies showcasing best practices for sustainable development in Romanian mountain tourist areas, alongside comparative analyses of European countries and regions with similar characteristics. The final section examines key challenges and real opportunities for sustainable mountain tourism in Romania. It highlights the potential impact of transformative trends like Industry 4.0 and, more importantly, Society 5.0, which could shape the sector’s future within the broader context of societal evolution.