The Discrete Cosine Transform (DCT) is a key component in image and video compression systems due to its high energy compaction and efficient implementation. This paper presents a hardware accelerator for the 2-D DCT integrated into RISC-V–based FPGA systems. The design relies on an optimized 8-point 1-D DCT algorithm requiring only 11 multiplications and 29 additions, extended to 2-D using row–column decomposition. The accelerator employs a three-stage pipeline performing row-wise transform, column-wise transform, and quantization. It was integrated with both MicroBlaze V and CVA6 RISC-V cores and implemented on AMD VCU128 and KCU116 FPGA development boards. Experimental results for multiple image resolutions show significant performance improvements compared with the software implementation, achieving speedups of up to 44.56× and a throughput of 2 Mpixel/s at 100 MHz. The accelerator uses modest FPGA resources, enabling multiple instances and demonstrating its suitability for accelerating image and video compression pipelines in RISC-V–based systems.