Background and Objectives: School-focused public food procurement and service policies (SPFPs) are increasingly being recognised as interventions that can improve the nutritional quality of food served in schools amidst growing overweight/obesity and persistent micronutrient deficiencies, stunting and wasting in sub-Saharan Africa (SSA). The review aims to investigate the impact of such policies on school food environments and nutritional outcomes of children/adolescents (5–18 y) in SSA and explore challenges and facilitators to implementing effective procurement. Methods: A mixed methods systematic review of studies in SSA published between 2012 and February 2023 was conducted. Studies were included if they reported on a publicly funded school meal (e.g., breakfast, lunch, snack, take home ration) and a nutritional (anthropometric, micronutrient deficiencies, food consumed) or food environment outcome. Quantitative findings were synthesised descriptively. Qualitative evidence was synthesized using an adapted eight-step school food system framework to guide coding (food production, wholesale & trading, transportation & storage, processing & distribution, food preparation, distribution to students, student-stakeholders and community involvement). This framework, along with infrastructure support domains, namely leadership, governance and monitoring/evaluation, guided categorisation of authors’ policy-related recommendations. Results: A total of 33 studies (26 qualitative, 7 quantitative) were included from nine SSA countries. Evidence from the quantitative studies was mixed and did not demonstrate any measurable impact of SPFPs on nutritional outcomes. In total, 53 implementation challenges, particularly in food distribution, food preparation and wholesale & trading, and 37 implementation facilitators, notably student stakeholders, community involvement and processing & distribution, were identified across the school food system. Infrastructure support and policy recommendations from authors span across the school food system, particularly for improving food preparation and engaging students in programming. Discussion: While little evidence on the impact of publicly funded school meal programmes and nutrition outcomes was found (partly explained by inadequate research design to evaluate impact), qualitative evidence suggests that developing or revising SPFPs to include healthy (nutritious and safe) food at all levels of the school food system has much potential. The array of policy action needed to improve implementation of school meal programmes across the school food system calls for action at multiple scales of governance (national/local government), as well as engaging schools and local communities to strengthen stakeholder involvement.