Sub-Saharan Africa has become the principal global site of digitally led financial inclusion. Account ownership in the region rose from 23 percent of adults in 2011 to 55 percent in 2021, with mobile money rather than conventional branch banking accounting for most recent gains: 33 percent of adults held a mobile money account, more than three times the global average, and all 20 economies worldwide where mobile money accounts outnumber bank accounts are in the region. This paper reviews the evidence on that transformation and its policy implications. It synthesises four literatures that are usually treated separately: cross-country measurement based on the Global Findex and industry statistics; causal evidence on the welfare effects of mobile money and digital credit; regulatory and fiscal analysis covering licensing, interoperability, consumer protection, data governance and transaction taxation; and critical political economy scholarship on the inclusion agenda itself. The review finds that first-order access has largely been achieved in leading markets while progress on usage depth, women's inclusion and consumer outcomes has been slower and in some respects negative. Effects on risk sharing and transaction costs are robust across studies; effects on savings, investment and poverty are smaller, context-dependent and methodologically contested. Access gains have introduced new risks, including over-indebtedness from algorithmic consumer credit, agent misconduct and fraud, exclusion through identity requirements, platform concentration, and revenue-driven transfer levies that measurably suppress the behaviour inclusion policy seeks to promote. Two findings deserve particular emphasis: the regional gender gap in account ownership widened from roughly 5 to 12 percentage points between 2011 and 2021 while narrowing elsewhere, an anomaly existing framework do not explain; and registered mobile money accounts exceed active accounts by roughly three to one. The paper argues that the policy frontier has shifted from enabling market entry to governing a maturing digital financial system, and sets out seven implications for regulators alongside a five-part research agenda.