This review highlights recent progress and perspectives on side-view operando optical microscopy (OM) on lithium-ion batteries (LIBs). Side-view operando imaging studies on LIBs offer new insights for understanding the dynamic feature of battery chemistry since the images or movies offer direct visualization of the most realistic conditions. Taking advantage of a fundamentally complete understanding, we have a chance to overcome the formidable challenges of the LIBs. For the realistic demonstration of each part of the battery components, OM has been used to understand direct electrochemical reactions identifying the fundamental failure mechanisms that help overcome the challenges of LIBs. Here, we provide a comprehensive review of our research work in the field of the application of OM for understanding the various challenging aspects of LIBs. Moreover, we highlight that the further utilization of the OM technique towards and beyond the LIBs could lead to the development of next-generation batteries.