In view of the hazards and degradation inertia of 4-nitrochlorobenzene (4-NCB), it is very important to detect the content of 4-NCB in water samples. Here, we developed a simple platform to accurately monitor the content of 4-NCB based on MnSe2/pyridine diketopyrrolopyrrole-grafted graphene oxide nanocomposite (MnSe2/PDPP-rGO) constructed glass carbon electrode (GCE) sensor. MnSe2/PDPP-rGO composited has been synthesized by two-step hydrothermal method, and MnSe2 nanoclusters composed of nanorods grows uniformly on the surface of PDPP-rGO lamella. Combined with electrochemical activity of MnSe2 to 4-NCB and the excellent conductivity of PDPP-rGO which have been confirmed by cyclic voltammetry and electrochemical impedance spectroscopy, the as-prepared MnSe2/PDPP-rGO/GCE displays outstanding electrochemical sensing comprehensive performance to 4-NCB with wide linear range of 0.05–280 μM, low limit of detection of 4.8 nM, long stability for up to 20 days, satisfactory interference and repeatability. These results provide sufficient basis for accurate and practical detection of 4-NCB based on MnSe2/PDPP-rGO/GCE platform.