In this work, we demonstrate the principle of mesoscopic construction of silk fibroin (SF) hybrid materials, which endows the materials with new performance. In implementing this strategy, mediating molecules, wool keratin (WK) molecules, were adopted to in-line synthesize Au nanoparticles (WK@AuNPs), which further create the stable linkage of AuNPs with SF nanofibril networks via templated β-crystallization. Fourier transform infrared spectroscopy, X-ray diffraction, and atomic force microscopy demonstrate that the mesoscopic hybrid network structure of the hybrid materials is different from neat SF materials, which gives rise to various new performances, that is, long-stable fluorescence emission. As the fluorescence emission can be characteristically annealed by Cu ions, therefore be adopted as the highly selective ion probes. Moreover, as WK@AuNPs are homogeneously connected to SF nanofibril networks, the carbonization of the materials leads to secondary hybrid materials of carbon-Au, where nano-sized Au particles are well distributed in carbonized mesoscopic conductive carbon networks. Such hybrid materials of carbon-Au can be further fabricated into electrochemical (i.e., dopamine) sensors, which are demonstrated to have excellent sensing performance.