Community health worker (CHW) programmes have been implemented in Kenya's semi-arid regions to address high child mortality rates. A mixed-methods approach including surveys, focus groups, and secondary data analysis was employed to assess programme impact on maternal and child health outcomes. CHWs provided essential healthcare services such as immunizations, nutrition counseling, and basic treatments, with a significant reduction in under-five mortality by 25% (95% CI: 18-32%). The CHW programmes significantly improved child health outcomes in the study area. Further training for CHWs is recommended to ensure consistent quality of care, and integration with existing healthcare systems should be explored. Treatment effect was estimated with $\text{logit}(p_i)=\beta_0+\beta^\top X_i$, and uncertainty reported using confidence-interval based inference.