Ten coumarin‐3‐formamido derivatives, N‐benzyl‐coumarin‐3‐carboxamide (2), N‐fluorobenzyl‐coumarin‐3‐carboxamide (3–5), N‐methoxybenzyl‐coumarin‐3‐carboxamide (6–8), N‐((1‐methyl‐1H‐imidazol‐5‐yl)methyl)‐coumarin‐3‐carboxamide (9), N‐(thiophen‐2‐ylmethyl)‐coumarin‐3‐carboxamide (10), and N‐(furan‐2‐ylmethyl)‐coumarin‐3‐carboxamide (11), were synthesized and characterized. Compound 5 crystallizes in a monoclinic system P21/c space group with four chemical formulas in a unit cell; molecules of compound 5 are self‐assembled into a two‐dimensional supramolecular structure by intermolecular hydrogen bonds and C⋯C π stacking. The potential anticancer effects of these compounds on HeLa (cervical carcinoma), MCF‐7 (breast), A549 (lung), HepG2 (liver), and human umbilical vein (HUVEC) cells were examined. Compared with compounds 1–8 and 10–11, compound 9 exhibits potent in vitro cytotoxicity against HeLa cells and lower cytotoxicity against normal cells. Therefore, further in‐depth investigations of compound 9 were performed. Absorption titration experiments and fluorescence spectroscopy studies suggested that compound 9 binds to DNA through the intercalation mode.