To investigate the compressive bearing performance of brick masonry walls reinforced with prefabricated autoclaved aerated concrete (AAC) panels, two brick masonry walls reinforced with double-sided prefabricated AAC panels and two unreinforced brick masonry walls as control specimens were designed and fabricated. Through compressive bearing capacity tests and finite element simulation software, the failure modes and compressive bearing performance of the brick masonry walls reinforced with prefabricated AAC panels were studied. Both the experimental and simulation results indicate that the reinforced layer of prefabricated AAC panels can provide confinement to the wall, delaying the cracking of the brick masonry wall and enhancing its compressive bearing capacity, ductility, and integrity. Compared to the unreinforced masonry walls, the compressive bearing capacity of the double-sided prefabricated AAC panel-reinforced walls increased by a maximum of 71.3% in the tests and by a maximum of 67.5% in the simulations. Based on the failure modes of the specimens and considering the contribution of the prefabricated autoclaved aerated concrete panel reinforcement layer, a formula for calculating the compressive bearing capacity of this reinforcement method was proposed. Furthermore, the strength utilization coefficient of autoclaved aerated concrete for this calculation method was fitted and determined based on the experimental and simulation results.