Water‐soluble fluorescent carbon dots (C‐dots) were synthesized through hydrothermal process using date pits pre‐treated with phosphoric acid as a carbon source. Transmission electron microscopy showed that the C‐dots have an average particle size of 1.1 ± 0.3 nm with a very narrow size distribution. The aqueous solution or the phosphate buffer solution (PBS) of as prepared C‐dots exhibits strong fluorescence when excited at 338 nm. The PBS solution of the as prepared C‐dots can inhibit growth by as much as 61% as well as migration of human lung cancer (A549), breast cancer (MCF‐7) and prostate cancer (PC3) cells at the concentration of 0.1 mg/ml. However, only 14% inhibition was observed for kidney (HEK293) cells at the same dose. In addition, the application of C‐dots was found to lead to the increase in thickness of the actin stress fiber, which may inhibit cell migration dynamics. Thus, nanomaterials such as date pits‐derived C‐dots may be applied as anti‐cancer agents.