The five were arrested on Saturday after a series of gun battles in the oil-rich emirate between security forces and insurgents that left four officers and eight suspects dead.
The men, originally stateless Arabs who had obtained Jordanian and Saudi citizenship, include three brothers, another relative and a neighbour. They were freed late on Monday.
"We have all been released after security men have established we were not involved in terrorist attacks or any of the events witnessed in the country recently," one of the men, Khalid Adhan al-Shimmari, told Al-Watan daily on Tuesday.
The Kuwaiti Interior Ministry, which on Saturday described them as "wanted men", did not announce their release, but a security official confirmed the report.
The five men surrendered to security forces after police fired shots and smoke bombs. There were no casualties.
Kuwait's Prime Minister Shaikh Sabah al-Ahmad al-Sabah said on Monday that he expected "terrorism will continue" in the emirate and warned it could spread to other Gulf states.