A method for the synthesis of unsymmetrical bis(indolyl)methanes (BIMs) using simple indoles and readily available alcohols as the coupling partners under both heat and 390–400 nm light conditions was developed. Detailed research of the mechanism demonstrated that the diaryliodonium salt‐mediated transformation undergoes a nucleophilic hydroxymethyl radical formation process. Moreover, the diaryliodonium salt‐mediated method is also applicable for synthesizing symmetrical BIMs.