The engineering industry is currently witnessing a high demand for composite materials due to their exceptional chemical and mechanical properties. Metal matrix composites (MMC) have become increasingly popular in the composites industry. The incorporation of biomass ash to enhance metallic matrices is a highly interesting topic of exploration. Biomass ash, a byproduct of biomass combustion, is often regarded as waste. The substantial consumption of biomass contributes to environmental pollution. The aim of this review is to enhance our understanding of the use of biomass ash in MMC applications by focusing on its mechanical, physical, chemical, and thermal properties. Varying types of reinforcement used in the matrix formation and areas of application of the MMC were also considered.