Globally, among different types of cancers, breast cancer is identified as the chief cause of mortality among females, and it is a challenge to find new effective treatment strategies with minimal side effects and increased efficacy. Plants are an integral part of the traditional indigenous healthcare system and are becoming the concrete source of new drug discovery. Thus, there is a need to obtain a scientific basis for applying traditionally used plants in cancer treatments that may harbour novel phytochemicals. Therefore, this study aims to investigate the antioxidant and anticancer potential of selected plants of ethnobotanical importance. Five plants of ethnobotanical importance were selected and screened to determine their antioxidant potential through various in vitro free radical scavenging assays (such as DPPH, ABTS, hydroxyl, and superoxide radical scavenging), ferric chelation, and total antioxidant potential, and the total phenolic and flavonoid content was estimated for the selected plants. In contrast, the anticancer potential of crude plant extracts was assessed using MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) against different breast cancer (MCF-7, MDA-MB-231, and MDA-MB-435S) and hepatic cancer cell lines (HepG2), and human PBMCs (peripheral blood mononuclear cells) were used for toxicity studies. The MTT results showed that among all of the crude plant extracts (CAN = Etlingera linguiformis, SES = Sesbania grandiflora, LEX = Smilax ovalifolia, DES = Desmodium triflorum, and CA = Chenopodium album), it was CAN and LEX that showed the best cytotoxic potential on exposed breast cancer cell lines in contrast to SES, DES, and CA. In addition, at the selected dosages that were exposed to breast cancer cells, none of the extracts from any of the five plants showed any cytotoxicity against human PBMCs. Thus, the crude extracts can be explored further for chemopreventive and anticancer activity on murine models to understand their underlying mechanism for effective cancer management.