Digital images are used in many areas. Because of that, digital image watermarking has become an important research topic by the view of protecting copyright. Several methods have being developed to protect the watermarking on the image from additional processes. DCT is one of the methods used for robustness of watermarking. In this work, Hardware/Sofware co-design image watermarking system is designed with using DCT on FPGA. Thus, transform operations are made faster via hardware. Watermarking method is made changeable easily with software.