Antler-type reishi mushroom (Ganoderma sichuanense) grown under blue LED light (460–475 nm) at 10 µmol m⁻² s⁻¹ produced the highest yields and bioactives, including 72.7 mg/g polysaccharides and 11.7 mg/g triterpenoids, significantly outperforming other light conditions. Blue light increased mushroom yield to 14.1%, compared with ~11% under natural, red, or white light, while also delivering the strongest boost to key medicinal compounds.