Lithium-ion batteries, the mainstay of current flexible devices, are nearing their theoretical limit for energy density, prompting the urgent need for alternative battery chemistries. Flexible lithium-sulfur (Li-S) batteries and analogous flexible alkali metal-chalcogen batteries are of great interest due to their high theoretical energy densities, enabled by multielectron chemistry. A Li-S battery uses sulfur as the cathode and lithium as the anode. Sulfur’s abundance makes Li-S batteries a cost-effective option, and their theoretical energy density is significantly higher than traditional lithium-ion batteries. However, challenges like the polysulfide shuttle effect and low sulfur conductivity are being tackled through approaches like solid-state electrolytes and nanostructured electrodes to improve conductivity and charge/discharge rates. With further research and development, Li-S and analogous alkali metal-chalcogen batteries have the potential to become a viable alternative to traditional lithium-ion batteries. They offer the potential for high energy density, low cost, and flexibility, making them a good fit for a wide range of applications. This chapter will provide a brief review of the challenges and opportunities of flexible Li-S and analogous alkali metal-chalcogen batteries.