The men were among a dozen Kuwaitis held at the US military
base since the 2001 US-led war in Afghanistan.
"The five arrived very late at night, after midnight," the ministry official, who declined to be named, told Reuters.
The men, who are expected to face a local court, flew home aboard a Kuwaiti plane on Friday carrying medical and security teams sent by the government.
They were identified as Saad al-Azmi, Mohammad al-Daihani, Adel al-Zamel, Abdullah al-Ajmi and Abdulaziz al-Shimmari.
The official said some family members were allowed to greet the men at Kuwait airport before they were whisked away by state security.
Others met the detainees at a military hospital where they will undergo medical tests.
"I saw all five, they look like they came out of a jungle; their hair and nails are long and dirty, they looked miserable," said Waleed al-Zamel, whose brother Adel, 42, is among the five.
"... they look like they came out of a jungle; their hair and nails are long and dirty, they looked miserable"
Brother of detainee
"We did not recognise him... He used to be a fun-loving person full of joy, now I saw someone who looks like a wild man. He keeps looking left and right, and he spaces out. He looks like he doesn't know if he is happy or sad," he told Reuters.
Hussein al-Ajmi said his brother Abdullah had told him about bad treatment at Guantanamo.
"All forms of psychological war was waged on them. They were put in small cells and their religion was insulted," he said.
The Pentagon has said the men's transfer came after a US military review that examines each case on its own. It said a total of 252 detainees have left Guantanamo since it opened in January 2002 and that approximately 500 remained.
Khaled al-Odah, chairman of the Families of Kuwaiti Detainees at Guantanamo committee, said Kuwait will hold talks with US officials to free the remaining six Kuwaitis, who include Odah's son, Fawzi, 27, a religious studies teacher.
About 500 detainees still remain
in the Guantanamo Bay prison
He was arrested in Pakistan near the Afghan border in 2001.
"It's difficult to speculate on when they will be released, but the general atmosphere points to relief," Odah told Reuters.
One former Kuwaiti detainee, Nasser al-Mutairi, was released from Guantanamo last January.
He was later tried and acquitted by a local court of charges that included joining al-Qaida and fighting a friendly nation, a reference to the United States.
But on Tuesday, an appeals court sentenced the 28-year-old Mutairi to five years in prison for "participating in hostile activities against a friendly country", and other offences.
Kuwait, a staunch US ally, is a main transit route for American forces going to Iraq. It was a launchpad for the 2003 war on Iraq and up to 25,000 soldiers are based there.