The current research sought to assess the effects of paulownia leaves extract (PLE) on performance, blood hematological, antioxidant activity, and immunological response of broiler chicken. In total, two hundred 1-day-old male Cobb500 chicks were allocated randomly into four equal treatments with 5 replicates. The first treatment served as a control (CNT) and was fed the basal diet only, while the other treated treatments were fed on the basal diet supplemented with 0.1, 0.3, and 0.5 g/kg diet of PLE, respectively. The performance results showed significant increments (P < 0.05) in live body weight (LBW), weight gain (WG), and European production efficiency factors (EPEIs) (linearly; p < 0.001) in cooperated with increasing PLE levels in broiler diets. At the same time, feed conversion ratio (FCR) and livability percentages were numerically enhanced under the effects of PLE supplementation. Moreover, a notable increase (P < 0.05 or 0.01) in oxidative remarks activity (GSH, glutathione; SOD, super oxide-dismutase and CAT, catalase) and elevated levels of immunoglobulin (IgM, immunoglobulin M and IgG, immunoglobulin G) were noted (P < 0.05) for treatments fed with PLE in a dosedependent manner. Also, a dramatic linear increase was observed in mRNA expression of IGF-1, GHR, IL-1β, and IL-10 genes of broiler chickens. This study concluded that enriched broiler feeds with 0.5 g/kg PLE might be a beneficial strategy to promote broiler health and production.