A concise synthesis of 6-formylindolo[3,2-b]carbazole (FICZ), a potent ligand of the aryl hydrocarbon receptor (AhR), has been established. The conjugate addition of the enolate derived from indolylacetate 2 to 2-chloro-3-formylindole 3 was accomplished. The following cyclization reaction under the acidic conditions gave the indolo[3,2-b]carbazole skeleton.