OBJECTIVES: Late treatment initiation threatens the clinical and public health benefits of antiretroviral therapy (ART). Quantitative synthesizes of the existing evidence related to this are lacking in sub-Saharan Africa (SSA), which would help ascertain the best evidence-based interventions. This review aimed to systematically synthesize the available literature on factors affecting linkage to care and ART initiation among adults with HIV in SSA. METHODS: Systematic searches were undertaken on four databases to identify observational studies investigating factors affecting both HIV care outcomes among adults (age ≥19 years) in SSA and were published between January 1, 2015 and June 1, 2021. RevMan-5 software was used to conduct meta-analyses and Mantel-Haenszel statistics to pool outcomes with a 95% confidence interval and <0.05 level of significance. RESULTS: A total of 46 studies were included in the systematic review, of which 18 fulfilled requirements for the meta-analysis. In both narrative review and meta-analyses, factors related to health care delivery, individual perception, and sociodemographic circumstances were associated with late linkage to care and delays in ART initiation. CONCLUSION: This review identified a range of risk factors for late linkage to care and delayed ART initiation among adults with HIV in SSA. We recommend implementation of patient-centered intervention approaches to alleviate these barriers.