Lightweight geopolymer concrete (LWGPC) is a special type of concrete that is lighter than conventional concrete. Additionally, due to the lesser density of LWGPC, it is easy to handle and transport from one place to another during construction. To develop the LWGPC, lightweight aggregates such as granulated blast furnace slag (GBFS) and lightweight air-cooled blast furnace slag (LACBFS) are substituted in place of natural fine aggregates and coarse aggregate, respectively, to fulfil the lack of natural resources from the environment. Hence, geopolymer concrete (GPC) is primarily produced in the present study, including industrial waste granulated blast furnace slag (GBFS) as a substitutive material for NFA. This GPC consists of fly ash (FA) and ground granulated blast furnace slag (GGBFS) as binders with a ratio of 50:50 with different proportions of GBFS (0-100%) as the partial replacement of NFA, activated by a 12 M alkaline solution. The strength performance of GPC with the GBFS sand is evaluated in the first stage of the study. The microstructure of various GPC mixes is then analysed to investigate the influence of GBFS on the overall composition of GPC. The optimum content of GBFS and curing period of the GPC design mixes were chosen using the rational surface method of curve fitting for experimental data of strength parameters. Based on all the findings, the investigation results in GBFS content of 37 to 46 % as the substitution of NFA at 52 to 70 days curing period can be effectively utilised for the production of better sustainable GPC. By considering the optimum mix designation of GPC, the LWGPC was developed by varying the LACBFS as the replacement of NCA. It is found that the density and strength decrease by increasing the LACBFS aggregates (i.e. from 0-100%) due to its highly porous nature. Hence, the utilisation of GBFS and LACBFS waste in LWGPC is environmentally beneficial and has the potential to be used in sustainable construction practices.