Heavy metal ions (HMIs), particularly Hg2+, Fe2+, Pb2+, and Cd2+, are toxic to biological systems. These HMIs display a wide distribution in aqueous systems, and due to their bioaccumulation tendency, their prevalence, even at very low concentrations, results in serious health issues in humans. This warrants the availability of easily affordable, reliable, quick, and sensitive approaches for real‐time monitoring of the concentration of HMIs in aqueous environments. Herein, we present the synthesis of a novel hydrazone functionality‐based chromogenic probe that ensures selective and sensitive spectrophotometric sensing of HMIs. More specifically, the synthesis of 3‐(2‐(2,4‐dinitrophenyl) hydrazono) Penta‐1,4‐diene‐1,5‐diyl) diphenol referred to as HZ in the MS through a two‐step approach via the low‐cost precursors viz. Salicaldehyde, acetone, and 2, 4‐dinitrophenyl hydrazine (2, 4‐DNP) is presented. The unique functionality of the as‐synthesized HZ, well‐characterized via spectroscopic approaches, is demonstrated to facilitate the spectrophotometric sensing of Hg2+, Fe2+, Pb2+, and Cd2+ with detection limits as low as 0.74 μM, 1.46 μM, 0.75 μM, and 0.75 nM respectively. Importantly the spectrophotometric response of HZ is demonstrated to be very sensitive to the nature of HMI, which does ensure selective specification of the chosen HMIs. The sensing ability of the HZ is well within concentration ranges that include WHO‐recommended safe and toxic concentrations for these HMIs.