This review article focuses on the advancements in interfacial engineering for garnet-type Li7La3Zr2O12 (LLZO) solid-state electrolytes in solid-state lithium batteries (SSLBs). The authors discuss the challenges associated with interfacial properties, such as high interfacial impedance and chemical incompatibility between the electrolyte and electrodes, which can lead to side reactions and reduced battery performance. They explore various strategies to enhance interface compatibility, including the use of lithiophilic layers, in situ contaminant conversion, and conformal interface design. The article highlights the importance of these modifications in achieving high energy density, rate capabilities, and long-term cycling stability in LLZO-based SSLBs. The review also provides insights into the potential directions for future research, emphasizing the need for further fundamental and comprehensive studies to optimize interface design and realize the full potential of LLZO-based SSLBs.This review article focuses on the advancements in interfacial engineering for garnet-type Li7La3Zr2O12 (LLZO) solid-state electrolytes in solid-state lithium batteries (SSLBs). The authors discuss the challenges associated with interfacial properties, such as high interfacial impedance and chemical incompatibility between the electrolyte and electrodes, which can lead to side reactions and reduced battery performance. They explore various strategies to enhance interface compatibility, including the use of lithiophilic layers, in situ contaminant conversion, and conformal interface design. The article highlights the importance of these modifications in achieving high energy density, rate capabilities, and long-term cycling stability in LLZO-based SSLBs. The review also provides insights into the potential directions for future research, emphasizing the need for further fundamental and comprehensive studies to optimize interface design and realize the full potential of LLZO-based SSLBs.