Solvent-free organic reactions have proved to be sustainable and efficient strategy in organic synthesis. Current solvent-free approaches include mechanochemical, microwave-assisted, and ultrasound-irradiated methods. As a complementary strategy, photothermal materials may also be used in solvent-free chemistry, offering the advantage of utilizing eco-friendly solar energy. Polypyrroles, the black conjugated polymers, feature facile synthesis, high stability and excellent light-harvesting capability, enabling it to server as photothermal reactors to conduct solvent-free thermal-induced reactions. Here, a series of polypyrrole materials have been synthesized in the presence of various surfactants. The usage of dodecyl dimethyl betaine afforded PPy-BS, which achieved a highest photothermal performance (241°C under 100 W halogen-lamp irradiation). On this basis, PPy-BS was employed as a photothermal reactor for Diels-Alder, dipolar cycloaddition, and electrocyclization reactions under solvent-free conditions. All trials work well, affording good to excellent yields up to 90%. Notably, PPy-BS photothermal reactor exhibits excellent recyclability (over eight cycles without loss of the yields of the conducted model reactions), high loading amount of substrates, and upscaling to 1000 mg per batch. In brief, this study highlights the advantages of PPy-BS photothermal reactors for pericyclic reactions, offering a recyclable, up-scalable, and solvent-free platform for sustainable organic synthesis.