<p>Barley, the fifth most produced cereal globally, is predominantly utilized in malting, where steeping is a critical phase influencing the initial conditions for grain germination and development. The steeping index is a pivotal parameter for evaluating steeping efficiency, as it reflects enzymatic activity correlated with water absorption. Conventional methods for steeping index assessment, such as the Chapon test, are labor-intensive, subjective, and time-consuming, underscoring the need for alternative analytical techniques that are more efficient, require minimal sample preparation, and offer high accuracy and reliability. Time-domain nuclear magnetic resonance (TD-NMR) has emerged as a promising non-destructive analytical tool, providing rapid analysis with reduced analyst dependency. This study aimed to develop and validate a TD-NMR-based methodology for determining the steeping index. Barley varieties were subjected to steeping simulations, and TD-NMR results, based on transverse relaxation decay time (<i>T</i>₂), were correlated with the conventional Chapon test using multivariate partial least squares (PLS) regression. The calibration curve demonstrated a high correlation coefficient (<i>R</i>² = 0.975) and a low root mean square error of calibration (RMSEC) of 15.64. Precision tests demonstrated that the TD-NMR method showed lower variability (standard deviation: 15.9) compared to the Chapon test (22.8). Robustness evaluations indicated a coefficient of variation of 25.40% for TD-NMR, comparable to the conventional method (25.63%). Accuracy testing using a paired <i>t</i>-test revealed no significant differences between methods (<i>p</i> = 0.26). Industrial validation trials confirmed TD-NMR’s superior reliability and precision, establishing it as an effective alternative for monitoring the steeping index in industrial malting processes.</p>