All-solid-state batteries (ASSBs) are emerging as critical energy storage systems due to their potential for higher energy density, safety, and reliability, making them a research priority in renewable energy technologies. Among ASSBs, inorganic solid electrolytes (ISEs) and layered oxide cathode materials (LOCMs) have gained substantial attention for their high ionic conductivity, chemical stability, and electrochemical performance. However, the interface between ISEs and LOCMs plays a crucial role in determining overall ASSB performance, as interfacial issues can severely hinder lithium-ion transport and reduce battery cycle life. Despite extensive research, a comprehensive understanding of interfacial degradation mechanisms between LOCMs and ISEs in ASSBs remains incomplete and requires further investigation. Therefore, this review systematically examines the origins of poor thermodynamic and electrochemical compatibility, as well as the contact loss caused by volumetric changes in LOCMs. Integrative modifications of LOCMs are highlighted as effective strategies to mitigate these issues. Furthermore, advanced characterization techniques are discussed for their abilities to provide multiscale insights into interface structure and chemical valence.