Complementary to C–H bond activation, C–C bond activation has emerged over the past few years as an increasingly powerful tool to access and modify complex molecules. Ketones, owing to their versatility and availability, provide a significant platform for C–C bond activating reactions. Herein, we reported a β-carbon elimination strategy for alkene(sp2)–C(O) bonds to realize the olefination of unstrained enones via a vinyl palladium species, which delivers a series of conjugated polyene compounds. The protocol features broad substrate scope, excellent functional group tolerance and can be extended to dba (dibenzylideneacetone) substrates for olefination, alkynylation, arylation and amination, which demonstrates the generality of the approach and affords two valuable products in one pot. Furthermore, the late-stage functionalization of natural products (β-ionone and acetyl cedrene) and synthesis of natural products (piperine, lignarenone, novenone) highlight the potential utility of the reaction.