This study focuses on the experimental test and analytical evaluation of lightweight concrete-filled steel tubular (CFST) columns under axial compressive loading until failure. By substituting lightweight expanded clay (LECA) for coarse aggregate, fly ash for cement, and pumice sand for M-sand, lightweight concrete has been produced. These material substitutions aimed to lower the overall weight of the concrete while enhancing key mechanical properties, particularly compressive strength and durability. Extensive optimization of the mix was carried out to balance the strength and durability requirements with the reduced self-weight. The CFST columns in this study varied in diameter-to-thickness (D/t) ratios to understand how different tube geometries influence the structural performance and confinement effects of the lightweight concrete core. The primary aim of the study is to reduce the overall weight of the composite columns where the steel tubes filled with concrete contain an optimized percentage of LECA to maximize load-bearing efficiency. An axial load test was conducted on lightweight CFST columns to examine their load-deformation behaviour. For further validation, the results from the experiments will be compared with those derived from a finite element analysis (FEA) conducted using the software ABAQUS. This comparison will help validate the accuracy of the finite element model and provide insights into the load-bearing mechanisms at play in these lightweight CFST columns, potentially guiding the design of similar composite structures in future engineering applications.