This paper presents the efficient digital Ex-core Neutron Flux Monitoring System (ENFMS) based on Field Programmable Gate Array (FPGA), designed to precisely measure reactor power levels across a wide operational range from 10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−8</sup> % to 10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> %. Conventional analog based ENFMS inherently suffers from low system performance, complex maintenance, susceptibility to environmental noise, and issues related to chip obsolescence. To address these challenges, the proposed system employs FPGA based digital signal processing, implementing three optimized measurement modes, namely Pulse, Mean Square Value (MSV), and Current, to effectively cover the entire operational range. A linear interpolation algorithm also provides smooth and continuous transitions between overlapping modes. Furthermore, the System on Chip (SoC) architecture integrates all signal processing functions onto a single FPGA chip, significantly reducing system size, complexity, and power consumption. Experimental evaluations performed on a Xilinx Kintex UltraScale FPGA platform demonstrated a short latency of approximately 3.49 μs at a 500 MHz clock frequency, high data throughput of 8.0 GB/s, and power consumption of about 6.3 W. Moreover, the system exhibited excellent measurement accuracy with a low RMS error of 0.0197 V throughout the entire operational range. Consequently, the proposed digital ENFMS significantly improves potential applicability, accuracy, and maintainability, making it well suited not only for existing nuclear instrumentation systems but also for emerging reactor technologies such as Small Modular Reactors (SMRs).