A general, robust, and efficient method for the conversion of benzoic acids to 1,2,3-triiodoarenes and 1,2,3-trihaloarenes via a two-step synthesis is reported. Commercially available benzoic acids were used that can allow the reactions to be performed on multi-gram scales with good-to-excellent yields. This report discloses a practical method for the synthesis of 1,2,3-triiodoarenes and 1,2,3-trihaloarenes that is general in scope, scalable, and easy to workup and purify. A potential application of the target compounds as precursors for novel regioselective metal–iodine exchange reaction of 1,2,3-triiodoarenes was also demonstrated. It provided ortho-diiodoaryl derivatives in a high regioselective fashion that are useful intermediates in synthesis and indeed are hard to synthesize by any other means.