Spider silk is a natural material possessing unique properties such as biocompatibility, regenerative and antimicrobial activity, and biodegradability. It is broadly considered an attractive matrix for tissue regeneration applications. Optical monitoring and potential control over tissue regrowth are attractive tools for monitoring of this process. In this work, we show upconversion modification of natural spider silk fibers with inorganic nanoparticles. To achieve upconversion, metal oxide nanoparticles were doped with low concentrations of rare-earth elements, producing potentially biocompatible luminescent nanomaterials. The suggested approach to spider silk modification is efficient and easy to perform, opening up sensing and imaging possibilities of biomaterials in a noninvasive and real-time manner in bio-integration approaches.