The asymmetric synthesis of ent-fissistigmatin C is successively accomplished in 12 steps (longest linear sequence (LLS)). Relying on the enantioselective coupling of aliphatic aldehyde with 2-hydroxychalcone promoted by cooperative organocatalysts, the pivotal linkage of ent-fissistigmatin C between the flavonoid and the sesquiterpenoid fragment was stereoselectively established. An unprecedented final-stage radical cascade was also featured in this synthesis, which enabled the simultaneous establishment of the trans-decalin framework via forging two consecutive C-C bonds in one step.