Well-exposed onshore mass-transport deposits (MTDs) are rare in syn-rift settings, providing valuable outcrop-scale constraints on slope-failure processes that are commonly inferred only from seismic data. Here we document a previously unrecognized occurrence of MTDs within the Miocene Syatin Formation along the northwestern Red Sea margin near Quseir, Egypt. Two laterally extensive, well-exposed units (MTDs-1 and MTDs-2) are characterized in detail based on integrated field observations and satellite-based mapping, which constrain their plan-view distribution (∼250–450 m), tripartite structural organization (headwall, translational, and toe domains), and northeastward transport direction. The deposits record syn-rift slope-failure events during Early–Middle Miocene extension, controlled by the interaction of tectonically induced slope gradients and lithological heterogeneity within the Syatin Formation. Seismic shaking on syn-rift normal faults is interpreted as the most plausible trigger, with mechanically weak, fine-grained horizons providing preferential detachment surfaces. The Syatin MTDs provide a rare onshore analogue for submarine mass-transport systems along rifted margins and offer new constraints on syn-rift sediment dispersal, slope instability, and subsurface reservoir heterogeneity.