Graphene oxide (GO) has recently been considered one of the most promising carbon derivatives in nanotechnology. It has many excellent features such as tumor targeting ability, biocompatibility and low toxicity. Therefore, we conjugated docetaxel (DTX) to GO-PEG molecule and investigate its anticancer efficacy in prostate cancer cell line (DU-145). In order to obtain GO-PEG-DTX molecules, we conjugated the DTX via bonds to PEG chains pegylated to the GO surface. We also investigated the stability of GO-PEG-DTX in different biological fluids such as cell mediums, PBS and water in vitro conditions. GO-PEG-DTX has the highest zeta potential in water. In the current research SEM, UV-Vis, and FTIR analyses and zeta potential were utilized for the characterization of nano-sized GO-PEG-DTX. Anticancer efficacy of GO-PEG-DTX were then investigated in DU-145 prostate cancer cell line using MTT metod. The prostate cancer cells were treated by different concentrations of GO-PEG-DTX, GO-PEG, GO, and DTX (1-100 µg/ml) during 24, 48 and 72 h. The spectrophotometric analyzed values at 570 nm were recorded and analysed with Graphpad Prism7. IC growth inhibition values was determined. The data showed that the GO-PEG-DTX had a highly effective anticancer activity on prostate cancer cell lines after 24, 48 and 72 hours compared to other molecules. GO-PEG-DTX was found statistically significant in the DU-145 cell line (***p < 0.0001, **p < 0.001, and *p < 0.01). As a result, it can be said that PEGylated GO is an excellent nanocarrier system for the high anticancer activity of DTX. Loading of anticancer drugs using this type of graphene-based nano carrier and delivery to targeted tissues may find potential application in biomedicine.