Introduction Quantitative nuclear magnetic resonance (qNMR) spectroscopy is an analytical method based on the principles of NMR spectroscopy. The main advantages of this method are its simplicity, time efficiency, high accuracy and reproducibility, and it is a non‐destructive technique. Objective To evaluate and standardise the quality of Artocarpus lacucha heartwood. A method for quantifying its oxyresveratrol content using qNMR was developed. Methodology Proton (1H)NMR (400 MHz) spectroscopy was used to analyse the methanol‐d4 solution of a given amount of crude extract of A. lacucha heartwood using ethyl p‐methoxycinnamate (EPMC) as an internal standard. The qNMR methodology was validated in terms of its linearity and range, limit of quantification (LOQ), stability, precision, and accuracy for the determination of the oxyresveratrol content. Results The qNMR method was validated in terms of its linearity, range, LOQ, accuracy, precision, and stability. The quantitative determination of the oxyresveratrol content in the methanolic crude extract of A. lacucha was found to be 17% based on 1HNMR analysis, which proved to be a reliable method as the results were comparable to those obtained by high‐performance liquid chromatography (HPLC) analysis. Conclusions This study validated qNMR spectroscopy as a reliable analytical procedure to determine oxyresveratrol in A. lacucha heartwood. Therefore, this qNMR method can serve as an alternative to the classical HPLC methods for evaluating and standardising the quality of A. lacucha heartwood.