Objective: Andrographis paniculata (Family: Acanthaceae) is a well-known medicinal plant used in the Indian traditional system of medicine for the treatment of many chronic diseases. The present study was aimed to quantify secondary metabolites, determine antioxidant, and anticancer activity of ethanol extract of A. paniculata leaves. Methods: Leaf sample was macerated with ethanol solvent. Alkaloids, terpenoids, saponins, phenols, and flavonoids were quantified with standard calibrations. The antioxidant potential was tested using 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS), and ferric reducing antioxidant power (FRAP) assays. In vitro anticancer activity was evaluated using human epithelial type 2 (HEp-2) cell line. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay was used to estimate the cytotoxicity of the extracts. Apoptotic and necrotic effects were characterized by DNA fragmentation assay and fluorescence microscopy using the dual acridine orange/ethidium bromide (AO/EB) staining method. Results: The phytochemical analysis reveals the presence of alkaloids, saponins, phenols, flavonoids, terpenoids, and steroids. Alkaloids, terpenoids, saponins, phenol, and flavonoid content were recorded as follows: 9.84%, 8.42%, 13.94%, 44.37 mg gallic acid equivalent/100 g, and 904 mg quercetin equivalent/100 g, respectively. The antioxidant activity from DPPH, ABTS, and FRAP assays showed dose-dependent inhibition of free radicals. In cell viability tests, cell death with increasing extract concentration was observed. DNA fragmentation and AO/EB stain confirmed apoptosis and necrosis in extract-treated cells. Conclusion: The results indicate that A. paniculata is a promising source for the development of antioxidant and anticancer drugs.