Background: Primary health care (PHC) systems and their successes and challenges vary between and within countries. We elucidate the role of PHC on health status and universal health coverage (UHC) by describing the achievements and challenges of PHC systems in seven countries representing the three economic levels: high-income (Belgium, Australia), middle-income (South Africa, Thailand), and low-income countries (Cambodia, Ethiopia, and Nepal). Methods: We adopted a mixed-methods approach and (a) extracted quantitative data on the key health and universal health coverage index of countries and (b) conducted a scoping review of the PHC systems in these countries. We used key terms related to the following eight domains: service delivery, health workforce, health information system, health financing, medicines, and leadership and governance (the WHO’s building blocks for national health systems) and community participation and multisectoral actions (other pillars of PHC) to identify the relevant literature and searched six databases: PubMed, Scopus, Embase, PsycINFO, CINAHL, and Cochrane Library. A total of 58 articles were identified and included in this review; data were charted and synthesised narratively. Results: There is variation in health services coverage and health status across the three economic levels. Countries expanded access to PHC services using strategies like telehealth and CHWs but faced challenges in sustainability, workforce retention, and service quality. Community engagement and multisectoral actions helped, though gaps in governance, resources, and essential medicines hindered progress towards UHC. Conclusions: By addressing the challenges and leveraging successful strategies, countries can move closer to achieving the goal of universal health coverage and improving health outcomes for all.