A finite element model validated by experimental and theoretical verification was established based on prototype data and geological survey information, with reference to an offshore wind power project in Guangxi, to systematically reveal the force transmission mechanism and bearing characteristics of the implantable rock-socketed jacket with double grouting layers on the inner and outer sides. The vertical force transmission contributions of shear keys and the evolution of shear force and bending moment in the pile under different loading conditions were investigated, clarifying the influence mechanism of formation characteristics on the bearing performance of the three-pile jacket. The results indicated that the shear keys bore over 90% of the vertical load transfer. Specifically, the end shear keys made a major contribution during the bearing phase, while the top shear keys played a significant role in the load transfer phase and under tensile conditions. When the formation strength reached a certain value, the bearing capacity of the jacket foundation became primarily governed by its own characteristics. Under rock-socketed conditions, the failure mode shifted from “sliding failure” to “stress failure”. Additionally, in high elastic modulus foundations, the pile shear force rapidly transitioned to negative values near the rock-socketed section, coinciding with the peak bending moment location. In low modulus foundations, shear force and bending moment reversal occurred at the end of the grouted connection segment. The greater the elastic modulus of the foundation, the shallower the burial depth required for the pile shear force and bending moment to approach zero. The research findings can provide a theoretical basis and reference for the design of implantable rock-socketed jacket foundations in similar projects.