"This is the first boat carrying the UN flag to dock in Aden since the war began" in late March, governor Nayef al-Bakri told reporters at the Aden refinery port.
The ship is chartered by the World Food Program, which has tried repeatedly to deliver aid to the port city in recent weeks but failed due to continued Saudi airstrikes.
"This will be the first WFP chartered ship to reach the port in Aden," WFP spokeswoman Reem Nada told AFP shortly before the ship entered the harbor.
Vessels sent by the United Arab Emirates managed to reach Aden in May.
A humanitarian ceasefire declared by the United Nations earlier this month failed to take hold.
On March 26, Saudi Arabia and some of its Arab allies began to militarily interfere in Yemen's internal affairs by launching deadly air strikes against the Houthi Ansarullah movement in an attempt to restore power to the fugitive former President Abd Rabbuh Mansour Hadi, a close ally of Riyadh.
More than 3,000 people, including 1,500 civilians, have been killed over the past three months in Yemen, according to the United Nations. Some local sources put the number at 4,500.