Here we report a one-pot thermal decomposition assisted synthesis of nickel cobalt phosphide (NiCoP) hollow-nanospheres for simultaneous sensing of the Lead (Pb2+), Mercury (Hg2+) and Cadmium (Cd2+) ions in the groundwater samples. The as-fabricated sensor exhibits distinct peak potentials for Pb2+, Hg2+ and Cd2+ using anodic differential pulse stripping voltammetry technique. The peak separation ΔEP between Pb[sbnd]Hg and Pb[sbnd]Cd is 770 mV and 300 mV, respectively. The sensor exhibits an excellent selectivity, sensitivity and the limit of detection (LOD) of 1.59 nM, 2.52 nM and 1.70 nM for Pb2+, Hg2+ and Cd2+ ions, respectively which are below the prescribed maximum contaminant level goal (MCLG) values. The sensing ability of the sensor is attributed towards the high surface area of the as-synthesised NiCoP hollow nanospheres with the presence of orthorhombic plane Co2P as electrocatalytic active sites and the excellent conductivity. The sensor is successfully employed in the determination of heavy metal ions (HMIs) in groundwater samples with an excellent recovery percentage. This is the first report, on the successful demonstration of NiCoP as an active material for simultaneous detection of HMIs which can be effectively used for various environmental analysis. © 2020 Elsevier B.V.