Polysiloxane/polyethylene graft copolymers can synergistically combine the distinguished properties obtained separately in polyethylene (PE) and polysiloxane and therefore attract considerable attentions from both academia and industry. Herein, we introduce a novel and efficient heterofunctional condensation approach to synthesize well-defined polydimethylsiloxane graft PE (PDMS-g-PE) under mild conditions. The chemical structures of PDMS-g-PE are characterized unambiguously, and the correlation between reaction conditions and the structural parameters of PDMS-g-PE is established. Scanning electron microscope images show that the obtained graft copolymer PDMS-g-PE can compatibilize the immiscible PE/silicone oil system.