<p>Reinforced soil retaining walls are widely used in land reclamation, embankment construction, and pavement engineering. Owing to complex terrain and alignment changes, angular retaining walls are frequently adopted in practice. However, existing studies mainly focus on straight walls, and the stress–deformation behavior of angular reinforced soil retaining walls under surcharge loading remains unclear. In this study, a physical model of an angular reinforced soil retaining wall was developed. A multi-source monitoring system integrating fiber Bragg grating (FBG) sensors, earth pressure cells, and displacement gauges was established, and numerical simulations were conducted using FLAC^3D. The strain evolution, deformation characteristics, and failure patterns under staged uniform loading were systematically investigated. The results show that the corner zone is the most critical area, exhibiting pronounced stress concentration. The micro-strain in the angular segment is generally higher than that in the straight segment and increases with wall height, corresponding to the area of lowest stability at the upper corner. The wall deformation pattern is characterized by larger displacements in the upper section and smaller ones below. Correspondingly, the peak micro-strain shifts progressively toward the area directly under the loading plate with increasing surcharge. Cracks are concentrated at the corner, and the potential failure surface has a logarithmic spiral pattern. These findings validate the applicability of FBG sensing for stress–strain monitoring in angular reinforced soil retaining walls, offering practical guidance for instrumentation layout and stability assessment in complex terrains.</p>