The Number Theoretic Transform (NTT) is a foundation of Module-Lattice-Based Cryptography (MLBC), yet its implementation can be resource-intensive, posing challenges for deployment on low-power and constrained devices. This paper introduces LightNTT, a high-efficiency NTT/iNTT core specifically architected for ML-DSA, emphasizing minimal resource utilization and optimal performance. LightNTT leverages a constant-geometry dataflow combined with a deeply pipelined single butterfly unit and an optimized Barrett modular multiplier to achieve a compact footprint. Implemented on an Artix-7 FPGA, the design consumes only 590 LUTs, 158 FFs, 2 DSPs, and 2.5 BRAMs. It computes a full 256-point NTT/iNTT in 1056 clock cycles, achieving a latency of \(3.49\mu \text {s}\) at a clock frequency of 300 MHz. Critically, LightNTT demonstrates a superior Area-Time Product (ATP) of 5.82, which is approximately 29% better than comparable state-of-the-art implementations of small designs. This work underscores the effectiveness of synergistic architectural and modular arithmetic optimizations in developing practical PQC accelerators for resource-limited environments.