Due to their ubiquity in nature and frequent use in organic electronic materials, benzothiophenes are highly sought after. Here we set out an unprecedented procedure for the formation of benzothiophenes by the twofold vicinal C−H functionalization of arenes that does not require metal catalysis. This one‐pot annulation proceeds through an interrupted Pummerer reaction/3,3‐sigmatropic rearrangement/cyclization sequence to deliver various benzothiophene products. The procedure is particularly effective for the rapid synthesis of benzothiophenes from non‐prefunctionalized polyaromatic hydrocarbons (PAHs). Thio‐fusion: Benzothiophenes are accessed from non‐prefunctionalized arenes in a one‐pot sequence involving an interrupted Pummerer reaction, 3,3‐sigmatropic rearrangement, and cyclization. The process does not require metals, proceeds by twofold C−H functionalization, and can be used to achieve the straightforward π‐extension of polyaromatic hydrocarbons.