Novel artificial tissues with potential usefulness in local-based therapies have been generated by tissue engineering using magnetic-responsive nanoparticles (MNPs). In this study, we performed a comprehensive in vivo characterization of bioengineered magnetic fibrin-agarose tissue-like biomaterials. First, in vitro analyses were performed and the cytocompatibility of MNPs was demonstrated. Then, bioartificial tissues were generated and subcutaneously implanted in Wistar rats and their biodistribution, biocompatibility and functionality were analysed at the morphological, histological, haematological and biochemical levels as compared to injected MNPs. Magnetic Resonance Image (MRI), histology and magnetometry confirmed the presence of MNPs restricted to the grafting area after 12 weeks. Histologically, we found a local initial inflammatory response that decreased with time. Structural, ultrastructural, haematological and biochemical analyses of vital organs showed absence of damage or failure. This study demonstrated that the novel magnetic tissue-like biomaterials with improved biomechanical properties fulfil the biosafety and biocompatibility requirements for future clinical use and support the use of these biomaterials as an alternative delivery route for magnetic nanoparticles.