In Taiwan, ceramic tiles are commonly used for exterior façade cladding with technical and aesthetical advantages. However, owing to long-term outdoor climate exposure and building component aging degradation, the deterioration of exterior wall tiles takes place, resulting in health and safety hazards (e.g., chip, flake, fall off). Therefore, tile adhesive mortar is essential for durable adhered tile façades. To reach net zero emissions by 2050, decarbonization of buildings is crucial so sustainable and energy-efficient solutions are desired for building façades. To improve the traditional cement mortar for wall tile installation, aerogel-based cement mortar was prepared in this study by incorporating silica aerogel power into cement mortar. Different synthesis approaches were examined and optimized for high compressive strength and low thermal conductivity. The thermo-mechanical properties of the synthesized aerogel-based cement mortar were measured. By optimizing the mix proportions, the lightweight aerogel-based cement mortar offers excellent thermal insulation performance for adhered tile façades, with reductions of 50% in the thermal conductivity and density compared with the traditional cement mortar. The compressive strength of the synthesized aerogel-based cement mortar meets the requirement of class CSIII as stated in EN 998-1: Specification for mortar for masonry standard. Furthermore, full-scale tests were conducted in two identical test houses (3m Width*4m Length*3m Height) with adhered tile façades, and one house used the synthesized aerogel-based cement mortar as the tile adhesive. The energy-saving potential of the aerogel-based cement mortar was assessed by comparing the energy consumption for cooling in two houses. The findings in this study demonstrate that the aerogel-based cement mortar can be a suitable tile adhesive worthy of further research and application in energy-efficient building façades.