Over the past two decades, in numerous experimental setups, Nitrogen-doped graphene (N-G) demonstrated their efficacy as highly functional carbon-based nanomaterials exhibiting superior electrochemical activity, high conductivity, and remarkable stability. This chapter presents a comprehensive overview of the electrochemical performance and durability of N-G materials in energy conversion and storage systems. The discussion begins with their role as electrocatalysts in key electrochemical reactions including the oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER). Emphasis is placed on comparing the catalytic performance of N-G materials in alkaline and acidic environments, where factors such as the type and distribution of nitrogen functional groups critically influence reaction pathways and catalytic efficiency. The chapter further explores the application of N-G as electrode materials in energy storage devices such as batteries and supercapacitors. The combination of high surface area, conductivity, and active nitrogen sites enhances charge transfer, energy density, and cycling stability. A detailed assessment of performance durability is also presented, addressing challenges related to the loss of nitrogen functionalities, structural degradation, and aggregation during prolonged electrochemical operation. Experimental techniques such as cyclic voltammetry, galvanostatic charge discharge testing, and electrochemical impedance spectroscopy are discussed as diagnostic tools to evaluate performance stability. Through these analyses, the chapter provides insights into the structure–performance–durability relationships of N-G materials, identifying key parameters influencing their long-term operation.