Abstract: With the advent of flexible/wearable electronic devices, flexible lithium-ion batteries (LIBs) have attracted significant attention as optimal power source candidates. Flexible LIBs with good flexibility, mechanical stability, and high energy density are still an enormous challenge. In recent years, many complex and diverse design methods for flexible LIBs have been reported. The design and evaluation of ideal flexible LIBs must take into consideration both mechanical and electrochemical factors. In this review, the recent progress and challenges of flexible LIBs are reviewed from a mechano-electrochemical perspective. The recent progress in flexible LIB design is addressed concerning flexible material and configuration design. The mechanical and electrochemical evaluations of flexible LIBs are also summarized. Furthermore, mechano-electrochemical perspectives for the future direction of flexible LIBs are also discussed. Finally, the relationship between mechanical loading and the electrode process is analyzed from a mechano-electrochemical perspective. The evaluation of flexible LIBs should be based on mechano-electrochemical processes. Reviews and perspectives are of great significance to the design and practicality of flexible LIBs, which is contributed to bridging the gap between laboratory exploration and practical applications.