New stabilization method for in situ self-assembled homeotropic alignment layer was proposed. The benzoic acid derivative and mesogenic diacrylate were employed as in situ alignment agent and reactive monomer (RM), respectively. This alignment layer offers stable vertical alignment (VA) of liquid crystals (LCs) via photopolymerization of RM. The formation process of the stabilized alignment layer is very simple and involves doping of the VA agent and RM. The fabricated LC cell exhibited low residual direct current and stable VA properties during long term operation. Our definitive alignment method is useful in fabricating LC devices requiring high reliability.