Biodegradable polymers have been employed as encapsulants for transient, resorbable implantable devices due to moderate water permeability, mechanical flexibility, and biocompatibility, however most of them relatively lack inherent anti-biofouling properties. This limitation can lead to undesired protein adsorption, cell adhesion, and fibrotic encapsulation, compromising device function and biocompatibility, particularly for long-term implantation scenarios. Here, this study introduces a soft, stretchable, and anti-biofouling encapsulant engineered by integrating self-assembled organosilicon nanowire networks onto micropatterned biodegradable elastomers. The resulting hierarchical surface architecture imparts superhydrophobicity while preserving mechanical integrity, improving water barrier performance by up to 420% compared to unmodified films and retaining stability under cyclic strains. Integration into a transient, stretchable optoelectronic device enables prolonged operation in aqueous environments, and in vitro and in vivo evaluations demonstrate suppressed cell adhesion, reduced fibrotic tissue formation, and excellent biocompatibility, highlighting the potential for long-lasting, bioresorbable electronic implants.