Abstract This study investigates tropical cyclone (TC) outer size (R34) evolution during intensification over the western North Pacific (2001–2022). Based on R34‐decile changes as intensity increases, TCs are classified into upward‐decile, stable‐decile, and downward‐decile types. These types exhibit distinct evolutionary pathways: upward‐decile TCs expand quickly yet intensify slowly; downward‐decile TCs intensify rapidly with limited outer size growth; while stable‐decile TCs follow an intermediate path. These contrasting tendencies manifest in the rare co‐occurrence of rapid outer size growth (RG) and rapid intensification (RI). In upward‐decile TCs, active asymmetric deep convection in the outer core favors angular momentum imports and size expansion; in downward‐decile TCs, deep convection is more concentrated and symmetric in the inner core, which is conducive to intensification. These findings reveal a nonlinear relationship between outer size evolution and intensity change during intensification, offering new insights into TC development.