In 1524 or 1525, he was sent out by king Francis I of France to explore the region between Florida and Newfoundland for a route to the Pacific. He made landfall near Cape Fear on or around March 1, and after a short sojourn south explored the coast northward.
Somewhat later, he believed that he saw the Pacific on the other side of a very narrow strip of land. What he saw in reality was Pamlico Sound, behind the Outer Banks of Carolina. This mistake led mapmakers, starting with Vesconte de Maggiolo in 1527 and Giovanni's brother Girolamo da Verrazano in 1529, to draw North America as being almost split in two, the two parts connected by a thin land bridge on the east coast. It would take a century for this error to be corrected.
Further north, Verrazano discovered New York Harbour. The Verrazano Narrows Bridge, spanning the Narrows, commemorates his visit. He followed the coast further east and north to Maine, then returned to France by way of Newfoundland.