This research work investigates the technical viability of producing artificial lightweight aggregates from municipal solid waste incinerated bottom ash (MSWIBA), municipal solid waste incinerated fly ash (MSWIFA), and cement through an autoclaving process. Before pelletization, MSWIFA underwent a washing process, resulting in a reduction of approximately 95 % chloride and 75 % sulphate content. The production of lightweight aggregates involved a single-step pelletization process using a disc-type pelletizer with optimum conditions of pelletizer speed of 35-45 RPM, pelletization duration of 20-30 minutes, and water/solid ratio of 0.30-0.35. Various ratios of MSWIBA, MSWIFA, and cement were trialed out with a proportion of MSWIBA : MSWIFA : Cement = 50:25:25 yielding the best results. The green pellets were cured in an autoclave and optimized for pressure, temperature, and retention time. The aggregates developed through the autoclaving process at a pressure of 3 bar with a temperature of 120°C, and a holding time of 60 minutes exhibited a bulk density of ~846 kg/m3, water absorption of ~11.5 %, and single pellet strength of ~2.8 MPa. After carbonation, an increase of ~2.5 times in single pellet strength and a 21 % reduction in water absorption is achieved due to the formation of phases like tobermorite, calcite and jennite. The developed lightweight aggregates sequester ~5.2 % of CO2 into it and gainfully utilize ~75 % of municipal solid waste incinerated ashes. The spherical-shaped lightweight aggregates are in the range of 4-15 mm in size and can be used in making non-structural elements like bricks, blocks, and roof insulation. The leaching behavior of heavy metals from MSWI bottom and fly ash showed significant reduction upon incorporation into concrete, confirming effective immobilization through cement hydration products and compliance with united states environmental protection agency (USEPA) limits. The embodied energy analysis of lightweight aggregates (LWAs) made from MSWI residues demonstrated relatively low energy input for raw materials (5.63 MJ/tonne) due to minimal pre-processing, and highlighted the potential for further reducing overall energy through optimized transportation and manufacturing processes.