Flow is an optimal experience that has received particular attention in learning due to its potential association with enhanced learning achievement. However, the strength and direction of the putative flow-fulfillment relationship remain unclear. Therefore, a PRISMA-directed systematic review was conducted in 2022 to examine the empirical evidence for the flow-performance relationship, examine underlying mechanisms, and assess the quality of the current evidence. An online database was used to search for peer-reviewed articles examining the relationship between flow and sense of accomplishment in online courses. Results were collated into a narrative synthesis and meta-analysis. Thirty two articles met the inclusion criteria. The overall quality of the studies was fairly good, Pooled effect sizes (r = 0.48, [0.39;0.59]) indicated a moderate flow-performance relationship across a range of online education. However, current evidence cannot determine the causal direction of this relationship or the mechanisms that mediate it. The many conceptual and methodological challenges facing flow research are discussed and suggestions for future work are outlined.