Abstract We present an enhanced and highly sensitive impedance cytosensor on the basis of folate conjugated-polyethylenimine-carbon nanotubes (folate-PEI-CNT). Zeta potential measurements and UV–vis spectroscopy have been employed to characterize the surface modifications of folate-PEI-CNT. We next investigated the efficiency of this probe for screening HeLa cells whose surfaces over-express folate receptors. The detection results have been further demonstrated by using scanning electron microscopy (SEM). Finally, we investigated the sensitivity of this impedance cytosensor with a detection limit of approximately 90 cells mL−1 according to 3δ rule, as well as a linear detection range from 2.4×102 to 2.4×105 cells mL−1.