Succinonitrile (SN) based solid-state electrolytes (SSEs) have potential applications in lithium (Li) batteries due to their ease of preparation and high ionic conductivity at room temperature. Here, a novel SSE consisting of poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP), poly(methyl methacrylate) (PMMA) and Li_1.3Al_0.3Ti_1.7(PO₄)₃ with SN is fabricated, where PMMA is added to serve as a polymer matrix for better wettability of SN. Due to the addition of PMMA, improved room-temperature ionic conductivity of the SSE is resulted. More importantly, better interfacial contact as well as more stable solid electrolyte interphase (SEI) layer between SSE and Li anode can be also obtained. As a result, homo- geneous and dendrite-free Li plating can be achieved for over 1000 h in Li symmetric cells. When coupled with LiNi_0.5Mn_0.3Co_0.2O₂ cathode and Li anode, the proposed SSE delivers excellent cycling stability and rate capability in full-cells. By implementing SSEs with a polymeric wetting agent, this work provides fresh perspectives on stabilizing the interface between SSEs and Li metal anodes.