A substrate‑independent, solvent‑free route to UV‑responsive adhesive interfaces on glass is demonstrated. Initiated chemical vapor deposition (iCVD) was employed to conformally coat glass slides with ultrathin poly(allyl methacrylate) films, leveraging the low thermal and chemical footprint of the process to preserve a high density of surface‑bound allyl groups. A systematic study of deposition parameters identified a filament temperature of 190 °C as optimal for maximizing allyl retention without compromising film conformity or adhesion to the glass. Following coating, a tailored thiol–ene oligomer was applied and cured under UV irradiation, triggering rapid click‑type network formation between PAMA’s allyl functionalities and thiol groups. Lap shear tests revealed that PAMA‑modified glass exhibited a greater than three‑fold increase in adhesion strength compared to unmodified controls, alongside a shift in failure mode from interfacial detachment to cohesive fracture within the adhesive layer. The precise thickness control (<200 nm) and tunable surface chemistry afforded by iCVD enable customization of interfacial reactivity, while the solvent‑free, room‑temperature process minimizes substrate damage. This combined iCVD/UV‑click strategy offers a versatile platform for engineering robust covalent adhesion on diverse surfaces, with potential impact in microelectronics packaging, biomedical device assembly, and eco‑friendly manufacturing. Future work will explore the extension of this methodology to flexible polymers and textured substrates for advanced adhesion applications.