The review is devoted to the methods of introducing aryl functional groups to the CNT surface. Arylated nanotubes are characterized by extended solubility, and are widely used in photoelectronics, semiconductor technology, and bioelectrocatalysis. The main emphasis is on arylation methods according to the radical mechanism, such as the Gomberg–Bachmann and Billups reactions, and the decomposition of peroxides. At the same time, less common approaches are also considered. For each of the described reactions, a mechanism is presented in the context of the effect on the properties of functionalized nanotubes and their application. As a result, this will allow us to choose the optimal modification method for specific practical tasks.