Recent advances in next-generation energy storage devices have focused on flexible and wearable all-solid-state lithium batteries (ASSLBs), mainly because of their advantages in terms of safety and extensive applications. Among various technologies for the preparation of flexible electrodes, electrospinning is a straightforward operation and cost-effective mean for the facile fabrication of flexible nanofibers and the versatile design of nanofiber structure. Herein, current technologies for engineering electrospun nanofiber structures and their state-of-the-art implementation in flexible ASSLBs are reviewed. First, current strategies for nanofiber structural design, including advances in high-specific surface area, superior mechanical flexibility, and various nanostructures, are systematically discussed. Subsequently, the utilization of electrospun nanofibers in ASSLBs is reviewed. Electrospinning of flexible and highly ion-conductive solid-state electrolytes (SSEs) is emphasized, and current nanofiber structural designs for SSEs and electrodes for ASSLBs are introduced. Despite these advances, there have not been enough studies of the integration of versatile electrospinning techniques in nanofiber structural design for both SSEs and electrodes. In the final section, promising pathways to implement versatile electrospinning in flexible ASSLBs with superior electrochemical performance and stable cycling properties are discussed. Thus, this review provides a holistic overview of the state of the art of electrospinning for high-performance flexible ASSLBs, which could safely power next-generation flexible devices.