Expanded perlite aggregate (EPA) is an inorganic insulation material preferred because of its low thermal conductivity. In other respects, it has disadvantages in buildings because of its high moisture retention, sintering in case of fire, and fragility. This study aims to produce a clay-based insulation board by eliminating these disadvantages of EPA with aerogel modification. The sol-gel method was chosen, allowing low-cost aerogel synthesis in a laboratory and permitting the control of parameters throughout the process. The optimum synthesis process was designed by examining the acid and base variables in the process. The recipe obtained at the aerogel synthesis was used to constitute aerogel-modified expanded perlite aggregate (AEP). AEP particles were prepared with clay matrix under determined process conditions, and characterization tests were carried out. According to the results, aerogel modification prevents high-temperature sintering of EPAs. The AEPs and the aerogel-modified expanded perlite aggregate and clay (AEP/C) composites' density remained almost unchanged compared to the EPA and expanded perlite aggregate and clay (EP/C) control samples. Thus, this can be offered that the prepared boards are lightweight and can maintain low thermal conductivity. The results showed that the mechanical strength of the boards was slightly higher than the control samples and the aerogel modification has almost no effect on mechanical strength.