To investigate the bearing deformation characteristics of the expanded stiffened deep-cement-mixing pile in soft strata and establish a reliable predictive method for its bearing capacity, field comparative static load tests were conducted on six expanded stiffened deep-cement-mixing piles and three conventional concrete pile types, enabling systematic analysis of their load-settlement behavior, ultimate bearing capacity, and deformation stability. The test results show that the load–displacement curves of the expanded stiffened deep-cement-mixing piles exhibited a gradual-variation behavior with stable settlement development, and the ultimate compressive bearing capacity increased by approximately 12%~15% compared with the design estimate. In particular, the expanded stiffened deep-cement-mixing pile with an effective length of 9 m achieved an ultimate bearing capacity of 2 760 kN, which is higher than those of the 25 m bored cast-in-place pile and the 23 m prestressed concrete square pile, demonstrating a pronounced short-pile, high-capacity advantage; meanwhile, the minimum settlement range among different test piles is only 2.65 mm, indicating good consistency in bearing performance and deformation stability in soft soil. Regarding predictive models for bearing capacity, the exponential-power function model demonstrates the highest fitting accuracy compared to the exponential function and hyperbolic models, accurately simulating the load-settlement response from the elastic stage to the entire failure process, with particularly high agreement near the ultimate load, and is recommended as the preferred model for predicting the bearing capacity of the expanded stiffened deep-cement-mixing pile; in contrast, the hyperbolic model shows a sharp sinking trend in later-stage predictions, which is inconsistent with the measured gentle characteristics, indicating poor applicability.