Digital marketing has emerged as a prominent business tool in the tourism industry and, in recent years, has received growing attention from the marketing research community. Digital marketing enables tourism businesses and environmentalists to promote and communicate sustainability practices, encourage sustainable consumption, and shape consumer mindset. This chapter discusses several digital marketing tools and platforms used by both businesses and environmentalists to promote sustainability activities. It discusses the concept of sustainable tourism and considers several terms and concepts related to sustainability. The chapter then examines the role of digital marketing in promoting the sustainability of tourism organisations as well as in educating travellers about the environment and sustainable issues. It then evaluates how digital marketing tools are harnessed to promote sustainable practices and education, raise awareness of environmental and social issues, encourage responsible and ethical consumer behaviour, and encourage community engagement. Finally, some of the challenges—greenwashing and green labelling of tourism businesses—in utilising digital marketing in sustainable tourism are discussed.