Periodontitis is one of the most common inflammatory diseases that can eventually cause tooth loss in adults. For the successful regeneration of periodontal tissue, one of the most feasible ways is the development of functional guided tissue regeneration (GTR) membranes with improved osteogenic capability. Here, we fabricated electrospun silk fibroin (SF) nanofibrous membranes and designed a low-cost and eco-friendly strategy to modify the SF matrix via tannic acid (TA). In this process, the conformational transition of SF protein triggered by TA made a remarkable improvement in mechanical properties of the SF membranes. More importantly, TA could induce biomimetic mineralization and in situ growth of hydroxyapatite (HAp) on the surface of the SF nanofibrous matrix. Cell experiments demonstrated that TA-coated SF nanofibrous membranes after mineralization could facilitate the proliferation and osteo-differentiation of MC3T3 cells. Considering the effectivity and methodological simplicity, this TA-mediated modification is a promising method to prepare SF-based GTR membranes with better mechanical performance and osteogenic function.