Recent progresses in the field of Al-ion batteries have given directions to look for new electrode materials that can lead toward the enhancement of battery performance. Using the dispersion-corrected density functional theory calculations, we have examined the applicability of hexagonal BC3 as a cathode material for Al-ion battery by evaluating its stability, specific capacity, and voltage profile diagram of AlCl4-intercalated hexagonal BC3. Our results show that AlCl4-intercalated BC3 compounds are stable. We have found that there is a significant charge transfer from the BC3 system to AlCl4 indicating toward the oxidation of BC3 upon intercalation reaction. Several low-energy pathways are observed for the diffusion process, and it is observed that the AlCl4 diffusion is trouble-free in the two-dimensional plane of BC3, having a diffusion barrier as low as 0.38 eV. Moreover, we have observed that BC3 can provide a higher average voltage 2.41 V and specific capacity of 74.37 mAh/g. These findings suggest that BC3 could be a promising cathode material for Al-ion batteries. © 2017 American Chemical Society.