The poor interfacial contact between electrode materials and electrolyte has become a major obstacle to the development and application of solid-state batteries. In this work, we report a facile method to realize interfacial modification with the help of in-situ ultraviolet solidified gel polymer electrolyte, which is completely compatible with commercial LiFePO4 and cellulose membrane forming stable composite cathode and cellulose membrane-gel polymer electrolyte. Two intimate interfaces between LiFePO4 and gel polymer electrolyte as well as composite cathode and cellulose membrane-based composite electrolyte are achieved to facilitate fast transfer of lithium ions at the interface. The assembled solid-state cell exhibits lower interfacial resistance, reduced polarization, higher rate capability, and more stable cycling performance than other routine counterparts. This work provides a new way for fabrication of novel advanced solid-state electrolytes and electrodes for applications in solid-state batteries.