Despite the increasing interest in cellulose-derived materials in biomedical research, there remains a significant gap in comprehensive in vivo analyses of cellulosic materials obtained from various sources and processing methods. To explore durable alternatives to synthetic medical meshes, we evaluated the in vivo biocompatibility of bacterial nanocellulose, regenerated cellulose, and cellulose nanofibrils in a subcutaneous transplantation model, alongside incumbent polypropylene and polydioxanone. Notably, this study demonstrates the in vivo biocompatibility of regenerated cellulose obtained through alkali dissolution and subsequent regeneration. All cellulose-derived implants triggered the expected foreign body response in the host tissue, characterized predominantly by macrophages and foreign body giant cells. Porous materials promoted cell ingrowth and biointegration. Our results highlight the potential of bacterial nanocellulose and regenerated cellulose as safe alternatives to commercial polypropylene meshes. However, the in vivo fragmentation observed for cellulose nanofibril meshes suggests the need for measures to optimize their processing and preparation.