<p>On 16 June 2024, 6,526 shallow landslides were triggered by an extreme rainfall in southern Wuping County, Fujian Province, China, which damaged hundreds of houses, caused four fatalities, and left two people missing. Remote sensing interpretation, field surveys, hydrological monitoring, and numerical simulations were conducted to investigate the characteristics and initiation mechanisms of these landslides. A relationship between landslide spatial distribution and lithology was identified, with the largest number occurring in granite areas. Landslide density showed a spatial correlation with cumulative rainfall prior to slope failure, but a weaker correlation with the event’s total rainfall. Morphologically, landslide scars range from an elongated rectangle (47:1) to a circle. In terms of failure mechanism, slopes were progressively saturated by rainfall infiltration, which reduced matric suction and shear strength and ultimately triggered landslides. Notably, no positive pore-water pressure was observed during this process. Failure occurred along the interface between residual layer and the underlying completely weathered layer, because the cohesion of residual soil decreased more markedly upon saturation than that of completely weathered soil. The morphology of landslides is influenced by lithology. Landslides in granite and granitic porphyry areas exhibited larger areas and widths, whereas those in graywacke and metagraywacke regions generally showed longer lengths and steeper initiation slopes. In addition, compared with granite regions, the frequency of landslide-debris flow hazard chain was higher in graywacke and metagraywacke regions. This paper provides new insights into landslide initiation mechanisms and the lithological controls on landslide morphology and cascading hazards.</p>