Composite hollow fiber membranes (CHFMs) have emerged as a promising platform for gas separation due to their high surface-area-to-volume ratios, scalability, and compatibility with high-performance polymers. However, it is a grand challenge to achieve defect-free thin selective coatings with minimal polymer intrusion into porous supports. We here report an air-assisted dip-coating strategy that effectively balances coating uniformity and minimal polymer penetration, enabling the fabrication of high-selective CHFMs. Fluorinated polyamic acid (fPAA) precursors dissolved in DMF were deposited onto ceramic hollow fiber (HF) supports, followed by in-situ air injection at varying flow rates during the withdrawal stage. This “surface solidification confinement strategy (SSCS)” induces rapid solvent evaporation and surface vitrification, effectively immobilizing the polymer layer and suppressing its infiltration into the support pores. Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy (SEM-EDS) and depth-resolved X-ray Photoelectron Spectroscopy (XPS) analyses confirm significantly reduced penetration with increasing air flow rate, yielding well-defined, defect-free selective layers. Gas permeation tests revealed enhanced H2/CH4 and CO2/CH4 selectivity, particularly at 20 L/min air injection, while subsequent thermal imidization of fPAA to fPI further improved performance (H2/CH4 selectivity ≈ 40; H2 permeance > 100 GPU). The process maintains uniform coating along multi-fiber bundles and demonstrates consistent performance in long-term mixed-gas operation, highlighting its scalability toward module-level fabrication. This work establishes a mechanistically guided and scalable approach for producing high-performance CHFMs through interfacial control during dip-coating.