Background: The antioxidant potential of medicinal plants has been illustrated through many reports clearly depicting that plants are a rich source of antioxidants, making them a great resource of novel drugs and health-care products. Objectives: The current study is, therefore, focused toward the assessment of antioxidant properties along with the presence of phytochemicals in leaves of 18 varieties/accessions of Aegle marmelos. Materials and Methods: The antioxidant activities were initially measured using superoxide radical scavenging method, 2, 2-diphenyl-1-picrylhydrazyl (DPPH), and ferric-reducing ability of plasma assays. Further, thin-layer chromatography (TLC), high-performance TLC, and column chromatography were performed to isolate the potentially active fraction and anti-inflammatory activity of crude, and the isolated fraction was tested on J774 macrophage cell line. Results: The maximum inhibition of superoxide anions was shown by Pant Aparna. Additionally, Pant Aparna extract was most efficient, exhibiting 92.0% inhibition in scavenging the DPPH radicals. The content of total carotenoids was found to be higher in Pant Aparna among all the varieties/accessions. Furthermore, the crude extract and the fraction A. marmelos methanolic fraction 21 (AMMF21) were found to be nontoxic and significant reactive oxygen species, and NO inhibition was observed in a concentration-dependent manner. Moreover, the methanolic extract of variety Pant Aparna showed promising in vitro antioxidant activity, indicating its potency for therapeutic applications. Conclusion: In brief, this is the first ever report on Pant Aparna as the best variety in terms of phytocompounds and identification of potential antioxidant activity. In addition, the AMMF21 fraction of methanolic extract possessing best antioxidant activity on macrophage cells indicates its use as a novel phytotherapeutic agent.