Mitochondrial plasticity is a key regulator of cell fate decisions. Mitochondrial division involves Dynamin-related protein-1 (Drp1) oligomerization, which constricts membranes at endoplasmic reticulum (ER) contact sites. The mechanisms driving the final steps of mitochondrial division are still unclear. Here, we found that microdomains of phosphatidylinositol 4-phosphate (PI(4)P) on Trans-Golgi network (TGN) vesicles were recruited to mitochondria-ER contact sites and could drive mitochondrial division downstream of Drp1. The loss of the small GTPase ADP-ribosylation factor 1 (Arf1) or its effector, phosphatidylinositol 4-kinase IIIβ (PI(4)KIIIβ) in different mammalian cell lines, prevented PI(4)P generation and led to a hyperfused and branched mitochondrial network, marked with extended mitochondrial constriction sites. Thus, recruitment of TGN-PI(4)P-containing vesicles at mitochondria-ER contact sites may trigger final events leading to mitochondrial scission.