Real-time digital audio processing plays a crucial role in modern electronic systems, such as mobile devices, communication platforms, and multimedia applications. However, ensuring high-performance, low-latency processing under hardware constraints remains a significant challenge, particularly when integrating audio codec chips with FPGA platforms. This paper presents the design and implementation of a real-time digital audio processing system using field-programmable gate array (FPGA) technology and the WM8731 audio codec. Firstly, a robust Inter-Integrated Circuit (I²C) interface is developed to configure the WM8731 codec, ensuring accurate initialization and stable operation. Secondly, a serial-to-parallel adaptor (s2p_adaptor) is designed to convert inter-IC sound (I²S) serial audio data into parallel format for digital processing, synchronized with bit and frame clocks. Finally, an 8-tap finite impulse response (FIR) filter is implemented using very high speed integrated circuit (VHSIC) hardware description language (VHDL) to enhance audio quality by suppressing high-frequency noise. All modules are synthesized in Quartus II and verified through ModelSim simulations and practical testing on an Altera DE1 development board. Timing diagrams based on the WM8731 datasheet and internal clock signals ensure precise synchronization. Experimental results demonstrate the effectiveness of the system, while final analysis highlights areas for further optimization and future improvements. Beyond audio applications, the proposed architecture is also adaptable to other real-time signal processing tasks, such as biomedical monitoring, radar front-end filtering, and image preprocessing. This extensibility enhances the system’s relevance in broader embedded and communication contexts.