An S-nitroso-N-acetylpenicillamine (SNAP) derivatization approach was used to modify existing free primary amines found in fibrin (a natural protein-based biomaterial) to generate a controlled nitric oxide (NO) releasing scaffold material. The duration of the derivatization reaction affects the NO release kinetics, the induction of controlled NO-release, hydrophobicity, swelling behavior, elastic moduli, rheometric character, and degradation behavior. These properties were quantified to determine changes in fibrin hydrogels following covalent attachment of SNAP. NO-releasing materials exhibited minimal cytotoxicity when cultured with fibroblasts or osteoblasts. Cells maintained viability and proliferative character on derivatized materials as demonstrated by Live/Dead cell staining and counting. In addition, SNAP-derivatized hydrogels exhibited an antimicrobial character indicative of NO-releasing materials. SNAP derivatization of natural polymeric biomaterials containing free primary amines offers a means to generate inducible NO-releasing biomaterials for use as an antimicrobial and regenerative support for tissue engineering.