Recent advances in wearable and embeddable displays have led to an increase in demand for functional coatings that are stretchable and also retain high optical transparency in fogging conditions. Herein, a conformal antifogging polymer thin film with exceptional stretchability was synthesized in a one-step manner using initiated chemical vapor deposition (iCVD). A series of polymer films were generated by copolymerization of a soft, hydrophilic 2-hydroxyethyl acrylate (HEA) together with a small fraction of a crosslinker 1,3,5-trivinyl-1,3,5-trimethylcyclotrisiloxane (V3D3). The composition of the film was precisely adjusted by controlling the flow rates of the input monomers in the vapor-phase deposition process to yield conformal hydrophilic antifogging films. Unlike conventional antifogging films that often lack mechanical durability due to excessive swelling, the iCVD-based antifogging polymer film offers the means to modulate the extent of crosslinking to achieve an excellent antifogging performance while imparting high elasticity with an elastic limit exceeding 300%. Detailed investigation of the antifogging performance and the mechanical properties through repeated cyclic stress-strain tests on sets of films with different compositions revealed that, in comparison to the commercial antifogging spray coating, the optimal iCVD-based antifogging copolymer film (pH8V1) maintains a high transmittance (>99%) upon exposure to hot water vapor, in the cold-fog transition test, and even in a stretched state.