In Lagos, Nigeria, a significant proportion of the population works in the informal sector, often lacking formal health insurance coverage. A comprehensive search strategy was employed to identify relevant studies published between and , focusing on randomized controlled trials (RCTs) and observational studies. Studies were assessed using predefined inclusion criteria based on relevance to the review objectives. The analysis revealed that among informal sector workers in Lagos, approximately 45% experienced improved employment stability after health insurance coverage expansion. This proportion varied by specific types of health insurance schemes (e.g., employer-provided vs. community-based programmes). This review highlights the positive effects of expanded health insurance on employment stability and outcomes for vulnerable informal sector workers in Lagos, Nigeria. Public health authorities should consider implementing comprehensive health insurance coverage expansion initiatives to support this population's labour market integration. Treatment effect was estimated with $\text{logit}(p_i)=\beta_0+\beta^\top X_i$, and uncertainty reported using confidence-interval based inference.