By means of density functional theory, detailed studies of regioselective chlorine-addition reactions of two C₅₄Cl₈ isomers disclose a highly competitive advantage of ^#540C₅₄Cl₈ in the chlorofullerene formation process. The regioselectivity of the addition pattern in ^#540C₅₄Cl₈ is found to be dependent on both local and general factors. Special structural relationships reveal that the pristine cage of ^#540C₅₄Cl₈ can transform to that of ^#864C₅₆Cl₁₀ and ^#913C₅₆Cl₁₂ through both C₂ addition and Stone–Wales rearrangement. It is found that Stone–Wales rearrangement, which is believed to be a high energy barrier reaction, can be facilitated remarkably well if chlorine atoms participate in the rearrangement process. Furthermore, investigation into the electronic properties of C₅₄ exohedral fullerenes reveal the different impacts of halogen and hydrogen atoms.