<p>A series of imido-vanadium(V) complexes bearing bidentate phenoxy-phosphine ligands were synthesized and characterized by NMR, elemental analysis, and single-crystal X-ray diffraction. These complexes demonstrated excellent catalytic performance in ethylene/1-hexene copolymerization, achieving high activities of 12.0×10⁶–49.0×10⁶ g_polymer ·(mol_V)⁻¹·h⁻¹ and affording random copolymers with tunable 1-hexene incorporations. These catalysts also exhibited ultrahigh activity, up to 112.2×10⁶ g_polymer ·(mol_V)⁻¹·h⁻¹, in ethylene/norbornene (NB) copolymerization, yielding cyclic olefin copolymers with adjustable NB incorporations. Remarkably, these catalysts demonstrated exceptional tolerance toward polar functional groups, enabling efficient copolymerization of ethylene with both 10-undecen-1-ol (U-OH) and 5-norbornene-2-methanol (NB-OH), incorporating about 2 mol% polar comonomers with high efficiency. Different with the catalytic behaviors in copolymerization of ethylene with nonpolar comonomers, the catalytic activities in E/U-OH copolymerization (25.7×10⁶ g_polymer ·(mol_V)⁻¹·h⁻¹) were much higher than those in E/NB-OH copolymerization (8.6×10⁶ g_polymer ·(mol_V)⁻¹·h⁻¹). DFT calculations revealed that the catalytic performance is governed by synergistic electronic and steric effects. For E/NB copolymerization, strong preference for cyclic olefins was attributed to favorable transition state stabilization. In polar comonomer systems, steric effects were predominant, with NB-OH exhibiting a larger buried volume around vanadium center upon coordination compared to U-OH. Overall, this work provides fundamental insights into vanadium-catalyzed (co)polymerization and offers new strategies for tailored polyolefin design.</p>