Metal-salen polymers are electrochemically active metallopolymers functionalized with multiple redox centers, with a potential for high performance in various fields such as heterogeneous catalysis, chemical sensors, energy conversion, saving, and storage. In light of the growing world demand for the development of superior energy storage systems, the prospects of employing these polymers for advancing the performance of supercapacitors and lithium-ion batteries are particularly interesting. This article provides a general overview of the results of investigating key structure-property relationships of metal-salen polymers and using them to design polymer-modified electrodes with improved energy storage characteristics. The results of independent and collaborative studies conducted by the members of two research groups currently affiliated to the Saint-Petersburg State University and the Ioffe Institute, respectively, along with the related data from other studies are presented in this review.