Catalysts for Claisen rearrangement have been intensively studied to overcome the need for high temperature. However, previous studies have encountered challenges, such as the need for heating, a long reaction time, and/or the need for equivalent amounts of catalyst. In this study, we introduce an effective electrogenerated boron-based Lewis acid catalyst for the aromatic Claisen rearrangement, which proceeds in a few minutes at ambient temperature. Generation of the electrogenerated Lewis acid catalyst is discussed based on NMR analysis and DFT calculations.