Biodiesel is an influential alternative fuel to petroleum‐based diesel fuel due to its nontoxic, biodegradable and renewable nature. Oxidation stability (OS) is a significant feature to analyze the stability and shelf life of a biodiesel. To prevent biodiesel from being oxidized, various antioxidants are being used. In the present work, the antioxidant activity of Phyllanthus emblica has been investigated to enhance the OS of jatropha biodiesel (JBD) and pongamia biodiesel (PBD) synthesized by transesterification. The evaluation of functional groups vital for antioxidative potential in P. emblica has been identified by Fourier Transform Infrared (FTIR) spectroscopy technique and the presence of the phenolic group in it contributes toward the slowing down of auto‐oxidation process in biodiesels. However, the antioxidant activity for it has been determined against 2,2‐diphenyl‐1‐picrylhydrazyl‐hydrate (DPPH) radical and total phenolic content (11.1 g of Gallic acid equivalent/100 g) was determined by the Folin–Ciocalteau method. OS of neat JBD and PBD was observed to be 4.24 h and 3.71 h, respectively. After doping P. emblica in different weight proportions, it has been found that the OS of JBD and PBD was increased up to 15.63 h and 14.26 h, respectively, with 1000 ppm blending. This study proves to be advantageous for exploring natural antioxidants to enhance the shelf life of biodiesels and to untarnish their renewable nature. © 2018 American Institute of Chemical Engineers Environ Prog, 38: 721–726, 2019