Nine pyrrole alkaloid derivatives, including four new ones (1–4), were isolated from the wild mushroom Lentinula edodes for the first time. Their chemical structures were determined using UV-Vis spectroscopy, IR spectroscopy, MS, NMR spectroscopy, and single-crystal X-ray diffraction techniques. Compound 1, a previously unreported bicylo-pyrrole aldehyde homologue, was found to be a major component, approximately 8.2 μg g ⁻¹ in the dry powder of L. edodes. Compound 1 showed cytotoxicity against SMMC-772 (IC₅₀ 15.8 μM) without any cytotoxic effect on LO2, a normal hepatic cell line; compounds 1 and 2 displayed weak immunosuppressive activities by inhibiting the proliferation of induced T cells; compound 3 showed inhibition activity on the proliferation of HaCaT cell line (IC₅₀ 25.4 μM) and weak antioxidant activity at a concentration of 50 μM.