Abstract Topological insulator nanostructures became an essential platform for studying novel fundamental effects emerging at the nanoscale. However, conventional nanopatterning techniques, based on electron beam lithography and reactive ion etching of films, have inherent limitations of edge precision, resolution, and modification of surface properties, all of which are critical factors for topological insulator materials. In this study, an alternative approach for the fabrication of ultrathin Bi 2 Se 3 nanoribbons is introduced by utilizing a diamond tip of an atomic force microscope (AFM) to cut atomically thin exfoliated films. This study includes an investigation of the magnetotransport properties of ultrathin Bi 2 Se 3 topological insulator nanoribbons with controlled cross‐sections at ultra‐low 14 mK) temperatures. Current‐dependent magnetoresistance oscillations are observed with the weak antilocalization effect, confirming the coherent propagation of 2D electrons around the nanoribbon surface's perimeter and the robustness of topologically protected surface states. In contrast to conventional lithography methods, this approach does not require a highly controlled clean room environment and can be executed under ambient conditions. Importantly, this method facilitates the precise patterning and can be applied to a wide range of 2D materials.