The alluring electronic, optoelectronic, and photonic properties of low‐dimensional materials have allowed brain‐inspired electronics to evolve in unprecedented ways. With highly efficient neuromorphic devices and architecture being concocted lately, an understanding of the underlying device mechanisms has emerged. The question of what types of materials and physical mechanisms will be used in future neuromorphic hardware is still open for debate. Herein, a critical review of the mechanisms among various configurations in state‐of‐the‐art low‐dimensional neuromorphic devices is presented. The factors are also reviewed that influence the working paradigm of low‐dimensional neuromorphic devices under different stimuli. Finally, a forward‐looking outlook on the challenges and perspectives in analyzing the mechanisms in this emerging research direction to drive next‐generation neuromorphic computing is provided. Brain‐inspired neuromorphic devices have attracted growing research interest for enabling next‐generation intelligent and autonomous systems. Underlying working mechanism in neuromorphic devices based on low‐dimensional materials is heavily based on device architecture and their electrical, optical, and photonic operating modes. This article presents an overview of the mechanisms among various configurations in state‐of‐the‐art low‐dimensional neuromorphic devices.