Laboratory tests for measuring crack width in reinforced concrete (RC) structural elements typically rely on conventional contact instruments such as linear variable displacement transducers (LVDTs), which are linked to a data acquisition system. However, these instruments are both costly and susceptible to damage when used in destructive tests. In this context, Digital Image Correlation (DIC) emerges as a promising non-contact optical alternative for crack monitoring at an affordable cost. This study utilizes two-dimensional DIC (2D-DIC) to comprehensively monitor crack development, accurately pinpoint their locations within the glass fiber-reinforced polymer (GFRP) RC beams, and precisely measure crack width across various loading stages. To validate the accuracy and reliability of DIC measurements, a full-scale GFRP RC beam was instrumented with several conventional LVDTs and subjected to a four-point bending until failure. The results obtained through DIC were then compared to the measurements derived from LVDTs. The findings indicate that the DIC technique offers a sufficient level of accuracy in crack monitoring and provides several advantages over conventional methods. This approach is particularly valuable for GFRP RC beams, where precise crack width data is crucial for design considerations. This study underscores the importance of digital image correlation as a powerful tool in structural health monitoring and maintenance of GFRP-reinforced concrete structures, contributing to their long-term durability and safety.