The current study examined the potential therapeutic advantages of catechin, either alone or in combination with docetaxel (DTX), against PC-3 prostate cancer cells. Following the MTT assay's determination of the IC concentrations, the cell lines were subjected to 48 h of treatment in the following protocol: untreated PC-3 control cells, docetaxel treatment, catechin (Cat) treatment, and DTX + Cat therapy at a ratio of 1:1. Treatments with DTX and Cat significantly decreased the number of viable cells in PC-3 cells in a dose-dependent manner. Additionally, the combo treatments caused the highest cytotoxicity compared with the other treatments. Also, when DTX and Cat were combined, they caused a significant synergistic effect (CI < 1) (combination index < 1). Furthermore, it was demonstrated that all treatments increased the expression of , , and mRNA in PC-3 cells while decreasing that of mRNA. The highest proportion of overexpression was observed in the combo therapy. A greater proportion of early and late apoptotic cells were caused by the combined treatment than by > DTX > Cat, according to flow cytometry. DNA damage in PC-3 cells was detected using the comet assay, and values of DNA tail, tail length, and tail moment increased considerably with increasing treatment dose. According to this study, Cat is effective against PC-3 cells when used in conjunction with DTX; by causing apoptosis, it enhances DTX's chemotherapeutic capability in cancerous cells.