Abstract Planetary boundary layer (PBL) turbulence modulates tropical cyclone (TC) intensity through competing mechanisms: (a) frictional dissipation that weakens TCs and (b) frictional convergence that drives stronger low‐level inflow and intensifies TCs. Three landfalling TCs (Beryl, Francine, and Milton) were simulated to examine how enhanced PBL turbulence affects TC intensity during landfall. Over the ocean, enhanced turbulence amplifies TC intensity through strengthening frictional convergence, low‐level inflow, leading to enhanced eyewall updraft and core downdraft, concurrently with higher surface latent heat flux, which maintains a warmer mid‐level core. Upon landfall, enhanced turbulence accelerates TC decay by strengthening frictional convergence and low‐level inflow. This process entrains cool and dry continental air from the PBL into the mid‐levels, reducing mid‐level moist static energy and producing a cooler core. These results demonstrate that boundary layer turbulence exerts opposing effects across the ocean–land transition through both dynamical and thermodynamical changes.