Herein, Bi(OTf)3-catalyzed Friedel-Crafts-type annulation of sulfonyl o-hydroxyacetophenones with benzofused cycloethers is described. This single-step strategy provides a variety of functionalized dibenzofused medium-size (9–12) oxacycles through the formation of carbon-carbon and carbon-oxygen single bonds. Further, the oxidative application of target oxacycles was investigated. The chemical structures of the key products were determined based on the single-crystal X-ray analysis. In the overall process, water was generated as the byproduct.