As the first contact point in a continuing healthcare process for individuals and families, primary healthcare has a prominent role in contributing to the achievement of Sustainable Development Goals (SDGs). Strong and effective primary healthcare is highly associated with significant health benefits such as a reduction in mortality rate, improvement of population health outcomes, and decreased costs in healthcare. The provision of quality primary care is the cornerstone of a sustainable healthcare system which is also ranked as a top priority in healthcare policy and research. In this chapter, studies examining the prominent roles of primary healthcare in relation to sustainable development will be discussed. This chapter will also focus on recent studies investigating new approaches to strengthen primary healthcare systems. Various reports on strategies and reforms for implementing sustainable primary healthcare will be further reviewed. Recently, the COVID-19 pandemic has further exposed challenges to the healthcare system which is already encountering heavy burdens due to the prevalence of chronic diseases and the ageing population worldwide. In this regard, critical issues arising from the impact of COVID-19 on the healthcare system and studies related to the implementation of primary healthcare in the pandemic context will also be discussed. The findings of this study are expected to provide further insights into health promotion and disease prevention, thus contributing to the development of a sustainable healthcare system founded on strong primary healthcare.