Jasmonates are class of plant growth regulators act as signal molecule that intercede various components in physiological and metabolic regulation, stress responses and possibly communication through signal transduction. Oxidative stress due to heavy metal exposure stimulates synthesis and activity of antioxidant metabolites and enhances antioxidant enzyme activities that could protect plant tissues. The aim of this study was to investigate the exogenous effect of JA at seed level which can transduce throughout seedling growth and regulate antioxidant activities such as superoxide dismutase (SOD; EC 1.15.1.1) and guaiacol peroxidase (POD; EC 1.11.1.7) in 12 days old seedlings of pigeon pea (Cajanus cajan (L.) Millsp.) in presence and/or absence of copper. The activity of SOD and POD increased significantly in presence of Cu²⁺ after seed priming with JA. JA also helps in chlorophyll and carotenoid accumulation and neutralizes the toxic effect of Cu²⁺ on seedlings. This is the first report of JA effect on photosynthetic pigment accumulation and H₂O₂ mitigating enzymes i.e. SOD and POD and it could be recommended that seed priming with JA help in ameliorating toxic effect of Cu²⁺.