Display omitted •Synthesis of PANI doped with Fe3O4 and GO hydrogels (H-PANI/Fe-GO) for selective and sensitive detection of heavy metal ions (HMIs) in aqueous solution.•The limit of detection (LOD) for the H-PANI/Fe-GO sensor was calculated by using the 3σ formula and was found to be 5.15 nM for Pb+2.•The selectivity of H-PANI/Fe-GO/GCE was examined in the presence of 1 μM of Pb+2 with 1 μM concentration of Cr+3, Fe+2, Ni+2 and K+ ions.•The reproducibility is an important parameter that was evaluated by using four different H-PANI/Fe-GO/GCE electrodes and its relative standard deviation (RSD) was found to be 4.194 % for Pb+2 detection, which is a clear indication that the electrode holds decent reproducibility.•The stability of the H-PANI/Fe-GO/GCE was verified by self-storing, the sensor displayed a stability retention of 97.23 % for Cd+2, 84.89 % for Pb+2, 92.00 % for Cu+2 and 96.96 % for Hg+2 over 14 days of stability. Heavy metal ion (HMI) pollution is threat to human health and environment. Here, a sensor for the electrochemical detection (ECD) of Pb+2 along with simultaneous detection of Cd+2, Cu+2 and Hg+2 utilizing the synergic effect of dopants like graphene-oxide (GO) and iron oxide (Fe3O4) into hydrogels of polyaniline (H-PANI/Fe-GO) displays an excellent square wave anodic stripping voltammetry (SWASV) performance towards Pb+2, with an impressive limit of detection (LOD) of 5.15 nM. The oxidative peaks were observed for simultaneous detection at −0.7306, −0.4899, −0.0092 and 0.3417 V vs. Ag/AgCl for Cd+2, Pb+2, Cu+2 and Hg+2 with good sensitivity, reproducibility and stability. Additionally, H-PANI/Fe-GO sensor is effectively employed to detect Pb+2 in real water samples.