Abstract Aromatic azo compounds have proven to be a relevant class of building blocks in chemical synthesis. However, uncontrollable selectivity towards azo compounds and low reactant conversion in traditional synthetic methods seriously impede their applications. Herein, Rb‐doped Au/CeO 2 nanocatalyst (Rb−Au/CeO 2 ) was prepared and utilized as a highly efficient supported metal catalyst for the selective oxidation of anilines to azocompounds using hydrogen peroxide as an oxidant, which reached ultrahigh selectivity (92 %) towards azoxybenzene and complete aniline conversion (100 %). The addition of Rb + accelerates the electron transformation of Au to produce Au + , which is ready for catalysis. This research presents a promising Rb‐doped strategy for achieving complete aniline conversion and high selectivity towards azoxybenzene, opening up new possibilities for the application of aromatic azo compounds in chemical synthesis.