The concept of establishing a base or even settlements on the Moon necessitates a thorough investigation into the building materials applicable for such projects. A leading approach in this endeavour is In Situ Resource Utilisation (ISRU), which advocates for the utilisation of lunar resources to reduce both the weight and costs associated with transporting materials from Earth. This study presents the concept of a geopolymer comprising lunar regolith simulant. Three distinct types of samples were analysed that were cured for 72 h at 60 °C; analogous samples cured at 20 °C; and a final set of samples were additionally subjected to reduced pressure. The analyses focused on comparing sample densities, compressive and flexural strengths. The experimental results indicated that it is possible to obtain geopolymers from lunar regolith simulants, which were cured at reduced pressure and exhibit mechanical strengths comparable to conventional structural material such as bricks.