Ruhal Ahmed, Asif Iqbal, Shafiq Rasul, Tareq Dergoul and Jamal al-Harith were repatriated to the United Kingdom on Tuesday.
Al-Harith was released immediately and the four others were held for questioning. But the four detainees were freed on Wednesday after police completed their interrogations.
However, Britons Feroz Abbasi, Moazzam Begg, Martin Mubanga and Richard Belmar are still in Guantanamo.
Human rights concerns
According to Home Secretary David Blunkett, they were captured in the "combat zone" in Afghanistan by US troops in 2001.
The release of the five coincided with a trip to Washington by a British delegation of intellectuals and human rights activists to condemn what they saw as a lack of basic due process for all Guantanamo detainees.
Around 660 prisoners suspected of being Taliban or al-Qaida fighters are being held without charges indefinitely as "enemy combatants" at Guantanamo Bay, a US naval base at the eastern end of Cuba.
Eighty-eight other prisoners of various nationalities have been released from Guantanamo, and a dozen others transferred to their home countries for continued detention, including seven Russians turned over on 1 March.