Gold nanoparticles (AuNPs) were assembled on the surface of polystyrene (PS) and polyaniline (PANI) core–shell nanocomposite (PS@PANI) for the immobilization of HL-60 leukemia cells to fabricate a cell electrochemical sensor. The immobilized cells exhibited irreversible voltammetric response and increased the electron transfer resistance with a good correlation to the logarithmic value of concentration ranging from 1.6×10 3 to 1.6×10 8 cellsmL −1 with a limit of detection of 7.3×10 2 cellsmL −1 at 10σ. This biosensor was simple, low cost and disposable, which implied that the PS@PANI/Au composites can regard as the potential applications for clinical applications.