Balzuhair, a citizen of Yemen, was arrested in Pakistan on Sept. 11, 2002, and arrived the following month at the US military facility in Cuba.
Last July, the Obama administration found that Balzuhair did not present a significant threat to national security. He had been described by US officials as a "low-level Yemeni militant" who received basic training at an al Qaeda camp in Afghanistan in mid-2001.
With his release, there are 59 detainees remaining at Guantanamo Bay, according to a Defense Department statement.
President Barack Obama has been working to shrink the number of detainees at the US facility in Cuba, but it appears he will leave office next Jan. 20 falling short of his goal to close the detention center amid opposition from many Republicans in the US Congress.
Cabo Verde is located in the Atlantic Ocean, about 350 miles (570 km) off the coast of West Africa.