Robust, non-delaminating polymer coatings and hydrogels are needed for technical and biomedical applications. This study focusses on surface-attached poly(oxanorbornene) hydrogels obtained by simultaneous UV-activated crosslinking and surface-immobilization. The synthesis and copolymerization of two oxanorbornene monomers carrying the UV-crosslinkers malonic acid diazoester or benzophenone, which can both undergo UV-triggered C,H-insertion crosslinking (CHic), is presented. The crosslinking efficiency and network stability of hydrogels made from these self-crosslinkable polymers are studied and compared to the properties of poly(oxanorbornene) networks obtained by UV-triggered thiol-ene-reactions involving a low molecular weight crosslinker. Smooth, defect-free, non-delaminating hydrogel coatings were obtained by CHic, not only on laboratory model surfaces but also on a technical product.