Accurate reconstruction of past Atlantic Meridional Overturning Circulation (AMOC), including its depth and strength, is essential for understanding past climate changes and the carbon cycle. However, major discrepancies remain among reconstructions of Last Glacial Maximum (LGM) AMOC geometry and strength from different proxy records. The conventional view that the LGM AMOC is shallower than at the preindustrial period (PI) has recently been challenged by studies suggesting similar AMOC geometry between the LGM and PI based on multiple proxies. Sedimentary ²³¹Pa/²³⁰Th records in the North Atlantic are influenced by both AMOC strength and depth, complicating their interpretation as a simple AMOC strength proxy, but provide a unique quantitative constraint on past AMOC structure. Here, using isotope-enabled ocean models, we show that AMOC geometry and strength can be robustly reconstructed from the vertical profile of Atlantic ²³¹Pa/²³⁰Th. Specifically, the depth of the mid-depth ²³¹Pa/²³⁰Th minimum reflects AMOC depth, whereas the minimum ²³¹Pa/²³⁰Th value indicates AMOC strength. Complied North Atlantic ²³¹Pa/²³⁰Th records suggest that the LGM AMOC was substantially shallower than during PI, while maintaining a comparable strength. These results improve the interpretation of sedimentary ²³¹Pa/²³⁰Th records and strengthen proxy-based reconstructions of past AMOC variability, providing new constraints on ocean circulation evolution during glacial climates.