<p>All-solid-state Li-ion batteries (ASSLBs) are believed to be capable of delivering higher energy density and better safety than conventional Li-ion batteries with an organic electrolyte. Oxide-based solid electrolytes have emerged as promising candidates for ASSLBs due to their wide electrochemical windows, excellent thermal stability, and good compatibility with high-voltage electrodes. This review provides a comprehensive and critical overview of recent advances in oxide Li-ion conductors, including NASICON, garnet, perovskite, and antiperovskite types. The underlying Li-ion transport mechanisms in relation to crystal structure, bottleneck size, defect chemistry, and the dimensionality of conduction pathways were analyzed. Primary emphasis is placed on the interfacial challenges between lithium metal and high-voltage cathodes, including chemical/electrochemical stability and lithium dendrite suppression. Moisture stability is discussed in detail to highlight important aspects of practical handling and processing. In addition, the review summarizes recent developments in hybrid polymer/oxide composite electrolytes, outlining how polymer-oxide interfacial engineering impacts ion transport and mechanical integrity. The review concludes with forward-looking perspectives on high-throughput computational screening, advanced characterization of buried interfaces, and integrated materials design strategies. This review aims to provide not only a structured summary of the current landscape but also actionable insights for future development of robust, high-performance oxide electrolytes for next-generation ASSLBs.</p> Graphical abstract <p></p>