Screening of new anticancer drugs and personalized medicine are of great significance for improving clinical cancer treatment and prolonging the lifespan of people diagnosed with cancers. Cell-based drug testing approaches that rely on complicated electrophysiological measurements or chemical activators and reporters are usually invasive and low throughput, therefore it is very imperative to develop an easy handling and efficient method to evaluate the efficacy of anticancer drugs. In this study, we present a simple and efficient method for pharmacodynamic evaluation based on optogenetics and graphene-based field-effect transistors (GFETs). This method involves the fusion of optogenetically engineered cancer cells and a GFET, in which the photoinduced bioelectricity of cells regulates the transistor output current. The experimental results showed that the light-dependent increment in the transistor output current of GFET falls dramatically upon the action of drugs, indicating the GFET with engineered cells can be used to evaluate drug efficacy. In addition, the drug efficacy evaluation with GFET is affected by the drain-source voltage, and the experimental results showed that drug efficacy can be better characterized at an appropriate drain-source voltage. These results demonstrated that the proposed method is effective and efficient for qualitative evaluation of drug efficacy. This method based on optogenetics and GFET is of significant value in drug screening and personalized therapies.