This paper reports modeling and simulation of polysilicon piezoresistors as sensing mechanism using commercial 0.35 μm complementary metal oxide semiconductor (CMOS) process. The CMOS-MEMS resonator is designed to detect change in mass. The designed piezoresistors are composed of two types; longitudinal and transverse. CMOS polysilicon thin film is used as the piezoresistive sensing material. The finite element analysis (FEA) software CoventorWare is adopted to simulate the piezoresistors and hence, compare its values with the modeled one. When actuation voltage is applied to the piezoresistors, it generates a change in resistance which is detected by the change in current. The percentage difference between simulated stressed and unstressed current is found to be 0.28 and 0.47 while the difference in the resistance between the model and simulation is 1.96 and 4.54 for the transverse and longitudinal piezoresistors, respectively. © 2015 IEEE.