The UDA, which has been on a ceasefire since 1994, had previously refused to disarm saying that Catholic Republican militias were still active.
The governments of Britain and Ireland, which have spent more than a decade pressing all of Northern Ireland's underground armies to disarm, welcomed the move.
Brian Cowen, the Irish prime minister, said it was "a further significant milestone in the peace process".
Shaun Woodward, Britain's secretary of state for Northern Ireland, said the move was pushed along by his threat to withdraw the amnesty period for handing over weapons.
He said the disarmament demonstrated "that firmness of government policy, with a clear deadline, have produced a startlingly strong outcome, removing some of the most dangerous weapons from the streets."
The UDA is the largest and last loyalist paramilitary group to hand over its weapons following the 1998 Good Friday Agreement which largely ended three decades of violence in the province known as the Troubles.
Loyalists are Northern Ireland Protestants who want the province to remain part of Britain and are historic foes of Catholic republicans, who believe the territory should become part of the Republic of Ireland.
The other main loyalist groups, Ulster Volunteer Force (UVF) and Red Hand Commandos (RHC), announced last June that they were putting all of their weapons beyond use.
The Irish Republican Army (IRA), the main republican paramilitary group, finished destroying its arsenal four years ago, overseen by the Independent International Commission on Decommissioning.