Israel had closed the Kerem Shalom during a violent flare-up in which Hamas militants fired an anti-tank rocket at a school bus, critically wounding an Israeli teenager, and Israel retaliated with air raids, killing 19 Palestinians.
The violence has subsided since Egyptian and U.N. mediators achieved an informal truce on Sunday.
"The crossing has reopened for business as usual," said Amir Koren, a spokesman for the Israeli military coordination office that oversees Gaza's border crossings.
Gaza traders said trucks from Israel first delivered animal feed and that basic food commodities were expected to pass through later.
On Tuesday, the United Nations Relief and Works Agency (UNRWA) which provides aid to more than two-thirds of Gaza's population of 1.5 million, said 172 truckloads of oil, sugar and flour were waiting to cross into the largely impoverished enclave.
Gaza shares a border crossing with Egypt at its southernmost point, Rafah, but commercial goods are brought in only via a monitored Israeli terminal. Smugglers bring in goods through tunnels dug beneath the desert frontier with Egypt.