Phytochemicals present in plants are more effective than their individual constituents in preventing cancer through synergetic effects. From this perspective, Shemamruthaa, a herbal formulation was evaluated with a view to potentiate more intense anticancer property. This study investigates the anticancer activity of Shemamruthaa in breast cancer (MDA-MB 231) cell lines and its cancer therapeutic potential in 7,12-dimethylbenz[a]anthracene induced breast cancer rats. Results of MTT, trypan blue, and apoptotic marker assays suggested that Shemamruthaa can induce cytotoxicity in cancer cells, in a concentration- and time-dependent manner. Oral administration of Shemamruthaa effectively suppressed the tumor progression as evidenced by decrease in tumor volume and modulation of oxidant-antioxidant status and resulted in extended life span. Gas chromatography-mass spectrometry and high-performance liquid chromatography analysis of Shemamruthaa revealed the presence of pyrogallol, 5-hydrxoymethylfurfural, trilinolein, and flavonoids. Finally, we show that Shemamruthaa contains potential anticancer agents acting either singly or in combination against breast cancer cell proliferation.