A metal-free and base-free Cl₃CCN mediated method was developed for the ipso-hydroxylation of aryl boronic acids to their corresponding phenols, which was promoted by a key unstable Lewis adduct intermediate. This transformation has broad functional group tolerance, and late-stage functionalization was successful as well. After simple investigation, two pathways (radical/ionic mechanism) were suggested, and the beneficial action of blue light needs to be further studied.