Abstract: This study aims to unravel the genetic mechanism governing the high-angle sharp bends of the Yellow River channel that cut across mountain ranges within the Lanzhou–Zhongwei Shapotou reach on the northeastern margin of the Tibetan Plateau, as well as to clarify the controlling effects of fault structures on the formation and long-term evolution of the river channel. Integrating field geological surveys, remote sensing interpretation, and regional geological analysis with tectonic geomorphology, this study focused on the geological structural characteristics of the two representative high-angle bend segments at Luoquanwan in Lanzhou and Wufo Township in Jingtai. The distribution and activity properties of fault systems were analyzed to evaluate their impacts on the spatial alignment of the Yellow River channel. Our results demonstrate that the Lanzhou–Zhongwei reach of the Yellow River is predominantly aligned along NE-, NEE-, and NW-trending fault zones, with particularly strong control exerted by NE-trending extensional strike-slip faults. These faults represent the key structural driver that facilitated river incision through mountain ranges and triggered channel avulsions. At both Luoquanwan and Wufo Township, the river did not follow the pre-existing NW–SE trending piedmont depression zones for natural downstream propagation, instead, it developed near right-angle sharp bends and cut across or obliquely traversed the NW-SE trending mountain ranges. The Yellow River channel predominantly develops within tectonic junctions and structural fracture zones formed by regional faults. The intersection, strike-slip, and thrusting of NE-trending and NW–NWW-trending faults collectively contribute to the short-line, high-angle bends of the river channel and its traversal of topographically elevated mountain systems. The Yellow River channel is primarily developed within tectonic junctions and structural fracture or fault crush zones formed by regional fault systems. Fault structures are the dominant controlling factor governing the channel extension and bending, particularly in driving the river to deviate from its original main course direction, dissect mountains, and traverse or obliquely cut across mountain systems via short-line, high-angle bends.