Turkish special forces crossed the Syrian border on Wednesday's morning.
The military operation backed by Turkish and US-led coalition warplanes aims to clear the Islamic State of Iraq and the Levant (ISIL) group from the Syrian border town.
70 targets in the Jarablus area had been destroyed by artillery and rocket strikes, and 12 by air strikes, military sources said.
President Recep Tayyip Erdogan said the operation was aimed against both IS and Kurdish fighters.
He is determined not to let the Syrian Kurdish forces fill the vacuum if IS leaves.