“These transfers were carried out under individual arrangements between the United States and relevant foreign authorities to ensure the transfers took place under appropriate security measures,” the Department of Justice said in a statement.
“Consultations with foreign authorities regarding these individuals will continue,” it added.
Yemenis account for almost half of the 198 detainees who remain at the U.S. military base in Cuba. But officials fear many could re-join militant groups if sent back to Yemen.
The Washington Post reported last week that the Yemeni transfers were the result of months of high-level talks with the government in Sanaa.
It said U.S. officials are prepared to repatriate more Yemenis if the transfer goes well.
Obama has pledged to shut the controversial detention centre in 2010, and announced last week that many of the detainees would be sent to a prison in the U.S. state of Illinois.
Some will face trials in U.S. criminal or military courts, while others are expected to be transferred abroad.