The electrode structure is a crucial factor for all-solid-state batteries (ASSBs) since it affects the electronic and ionic transport properties and determines the electrochemical performance. In terms of electrode structure design, a single-ion conducting solid polymer electrolyte (SIC-SPE) is an attractive solid electrolyte (SE) for the composite electrode among various SEs. Although the ionic conductivity of SIC-SPE is lower than other inorganic SEs, the SIC-SPE has a relatively lower density and can form an intimate contact between the SE and active materials (AM), resulting in an excellent electrode structure. The electrochemical performance of the cell with SIC-SPE was comparable with the cell with Li6PS5Cl (LPSCl), which has 10 times higher intrinsic ionic conductivity than SIC-SPE (SIC-SPE: 0.2 × 10−3 S cm−1, LPSCl: 2.2 = 10−3 S cm−1 at 25°C). 3D digital-twin-driven simulation showed that the electrode with SIC-SPE has a higher SE volume fraction, a lower tortuosity, and a larger AM/SE contact area than the LPSCl electrode. The favorable structure of the SIC-SPE electrode leads to lower overpotential than the LPSCl electrode during operation. Our results suggest that the SIC-SPE is a promising SE for making a good electrode structure in ASSBs.