<p>This paper presents a framework for localising a grout-injected rock fracture based on anomalous magnetic signals within the Earth’s magnetic field. The grout penetration area in a fracture is demonstrated to be magnetically detectable by simply incorporating magnetite powder into the grout. Assuming the grout spread resembles a thin dipping sheet, an inversion approach is introduced based on variations in magnetic anomalies caused by a vertically magnetized sheet. The inversion method correlates the geometric information of the sheet with changes in different components of magnetic anomalies observed at multiple levels. To address the limitation posed by obliquely magnetized source, a phase transformation method is proposed to convert the anomalous field to a vertically magnetized pole. The framework’s adaptability and efficiency are demonstrated through synthetic examples. Results indicate that the inversion approach effectively estimates the burial depth of deeply buried sources, despite some limitations in estimating dip angles and horizontal spans. Among the factors affecting inversion efficiency, elongating the sheet along its striking orientation and smoothing its corners have minimal impact on depth estimation. However, the developed approach falls short of isolating the interaction of multiple magnetic sources when the depth to length-down-dip ratio exceeds 1. It is recommended to perform separate magnetic observations for each sheet after the grouting process to improve localisation of multiple sources. This study provides a non-destructive alternative for detecting grout-injected rock fractures and can be extended to more complex scenarios in various field applications.</p>