AbstractLiFePO₄ (LFP) is widely used as cathode material for its low cost, high safety, and good thermal properties. It is one of the most exploited cathode materials for commercial Li‐ion batteries (LIBs). Herein, we present a screen‐printing method to prepare a LFP composite cathode, and a rational combination of the typical composite solid electrolytes (CSE) consisting of polyethylene oxide (PEO)/Li‐salt (LiTFSi) electrolyte with ceramic filler (LLZO or Li_6.4La₃Zr_1.4Ta_0.6O₁₂ (LLZTO)) has been successfully demonstrated for SSB. The prepared CSE offers: i) a promising ionic conductivity (0.425 mS cm⁻¹ at 60 °C), ii) a wide electrochemical window (>4.6 V), iii) a high Li‐ion transference number (tLi₊=0.44), iv) a good interfacial compatibility with the electrode, v) a good thermal stability, and vi) a high chemical stability toward Li metal anode. The Li/CSE/Li symmetric cells can be cycled for more than 1000 h without Li‐dendrites growth at a current density of 0.2 mA cm⁻². The final cell screen‐printed LFP composite cathode (LFP+LLZO)//Li metal displays a high reversible specific capacity of 140 mAh g⁻¹ (0.1 C) and 50 mAh g⁻¹ (0.5 C) after 1^st and 500^th cycles.