Macroautophagy　involves　the　encapsulation　of　cellular　components　within　double-membrane　autophagosomes　for　subsequent　degradation　in　vacuoles　or　lysosomes.　Coat　protein　complex　II　(COPII)　vesicles　serve　as　a　membrane　source　for　autophagosome　formation.　However,　the　specific　role　of　SEC24D,　an　isoform　of　the　COPII　coat　protein　SEC24,　in　the　macroautophagy　pathway　remains　unclear.　In　this　study,　we　demonstrate　that　SEC24D　is　indispensable　for　macroautophagy　and　important　for　autophagosome　closure.　Depletion　of　SEC24D　leads　to　the　accumulation　of　unsealed　isolation　membranes.　Furthermore,　under　conditions　of　starvation,　SEC24D　interacts　with　casein　kinase1　delta　(CK1　delta),　a　member　of　the　casein　kinase　1　family,　and　autophagy-related　9A　(ATG9A).　Collectively,　our　findings　unveil　the　indispensable　role　of　SEC24D　in　starvation-induced　autophagy　in　mammalian　cells.