Typical tropical cyclone (TC) attributes, including translation speed and intensity, have been demonstrated to affect TC intensification via modulating sea surface temperature (SST) cooling effect, while the effect of storm size is relatively less explored. Using satellite-observed SST during 2004–2021, we examine the effect of storm size on TC-induced SST anomalies (SSTA) and TC intensification in global TC-active oceans. In all basins, SSTA has the strongest correlation with 34-kt wind radius (R34), which is thus utilized as the representative storm size among various TC wind radii. Generally, large TCs generate stronger and more widespread SSTA than small TCs. Despite the same effect on prolonging residence time of TC winds, the effect of doubling R34 on SSTA is more profound than halving translation speed. Through the three-dimensional Price-Weller-Pinkel (3DPWP) experiments, how storm size influences ocean dynamic processes controlling SSTA is explored. Vertical mixing intensifies with storm size and primarily dominates both inner-core and outer-core SSTA. Upwelling increases with larger TCs and has a secondary effect on inner-core SSTA, while surface heat flux decreases and plays a minor role in outer-core SSTA. Horizontal advection becomes increasingly important in the cold wake asymmetry with storm size. This study further demonstrates that storm size regulates TC intensification through an oceanic pathway in all basins: large TCs induce stronger and more widespread SSTA, which reduces ocean’s enthalpy flux supply and thus suppresses TC intensification, as compared to small TCs. Moreover, small TCs, occupying weaker SST cooling and larger enthalpy flux, are more likely to undergo rapid intensification. Storm size varies greatly across global basins, and thus its effect on TC intensification through this oceanic pathway exhibits considerable inter-basin differences. Our results suggest that accurately representing storm size in TC coupled models, can potentially improve cooling estimation and TC intensity prediction.