Predicting interaction between toxic heavy metals in neutral charge state with graphene and a holistic understanding the interaction mechanisms are still very important tasks due to a strong necessity to develop reliable and real-time sensing applications providing the environmental control of toxic pollutants, especially in industrial regions of developing countries. By means of electrochemical measurements and density functional theory (DFT) modelling, we investigated the adsorption behaviour of three most toxic heavy metals (namely, Cadmium, Mercury and Lead) onto graphene and revealed the relationship between stripping current density and adsorption energy. Electrochemical results indicate that graphene exhibits different stripping behaviour toward heavy metal species, enabling only detection of the Cd and Pb. Comprehensive theoretical calculations explain the enhanced sensitivity of graphene to Pb through performing extended charge decomposition analysis (ECDA), noncovalent interaction (NCI) analysis and topological analysis.