UV exposure is harmful to plants. Increasing resistance against UV light is thus of great importance to their growth. Para-Aminobenzoic acid (PABA) has major roles in many biological processes, involving nucleotide biosynthesis, DNA repair, and DNA methylation, which contributed to UV irradiation. However, no study reports the effect of PABA on UV tolerance, or details of the underlying molecular mechanisms are explored. Hence, the objective of the research is to study the protective effect of PABA on UV in Arabidopsis and explored the molecular mechanisms. We overexpressed PABA synthase gene (Pabs) from Mushroom Agaricus bisporus in Arabidopsis and observed reduced root growth and UV-C hyposensitivity exposed to 2500 J m⁻² UV-C light. UV-C-induced DNA damage was significantly reduced and the expression of decreased DNA methylation 1 (DDM1) was remarkably higher in the Pabs lines, suggesting that overexpression of Pabs may protect against UV-induced DNA damage. In addition, overexpression of Pabs leads to an elevated reactive oxygen species production at root tips and enhanced catalase and superoxide dismutase activity, which may correlate with the enhanced UV tolerance of the Pabs overexpression lines. In summary, overexpression of Pabs from A. bisporus enhances UV-C tolerance of Arabidopsis, suggesting that Pabs takes an important part in defence against DNA damage.