Objective: To investigate bioactive phytochemicals and antioxidant activities of Nymphaea nouchali and to explore its anticancer pathways by a network pharmacology approach. Methods: Using a spectrophotometer and high-performance liquid chromatography-diode array detector (HPLC-DAD), we quantified bioactive phytochemicals in methanolic extract of Nymphaea nouchali tuber. The extracts were investigated for in vitro antioxidant properties. Targets of these bioactive phytochemicals were predicted and anticancer-associated pathways were analyzed by a network pharmacology approach. Moreover, we identified the predicted genes associated with cancer pathways and the hub genes in the protein-protein interaction network of predicted genes. Results: Quantitative results indicated the total phenolics, total flavonoids, and total proanthocyanidins in the methanolic extract of Nymphaea nouchali tuber. HPLC-DAD analysis showed rutin (39.44 mg), catechin (39.20 mg), myricetin (30.77 mg), ellagic acid (11.05 mg), gallic acid (3.67 mg), vanillic acid (0.75 mg), rosmarinic acid (4.81 mg), p-coumaric acid (3.35 mg), and quercetin (0.90 mg) in 1 g of dry extract. The extract showed the radical scavenging activities of 2, 2-diphenyl-1-picrylhydrazyl, 2,2'-azino- bis (3-ethylbenzothiazoline-6-sulfonic acid) and N,N-dimethyl-p phenylenediamine. By using network pharmacology, we predicted 130 target genes associated with cancer pathways. The top hub genes (IL6, AKT1, EGFR, JUN, PTGS2, MAPK3, CASP3, and CXCL8) were also identified, which were associated with cancer pathways and interacted with bioactive phytochemicals of the methanolic extract of Nymphaea nouchali tuber. Conclusions: Our study provides insights into the mechanism of anticancer activities of the methanolic extract of Nymphaea nouchali tuber.