Kenyan informal settlements face significant challenges in energy efficiency and cost management due to the use of traditional building materials. A comprehensive search strategy was employed using databases such as Web of Science and Scopus to identify relevant studies. Studies were screened based on predefined inclusion criteria and assessed using a pre-established quality assessment tool. The analysis revealed that the adoption of eco-friendly materials in informal settlements led to an average reduction in energy consumption by approximately 25% compared to traditional methods, with cost savings ranging from $10-$30 per month for households. Eco-friendly building materials offer a viable solution for enhancing energy efficiency and reducing costs in Kenyan informal settlements, although further research is needed to assess long-term sustainability impacts. Investment in eco-friendly material supply chains should be prioritised, along with public awareness campaigns on the benefits of sustainable housing practices.