Yahya Jammeh has agreed to cede power to new leader, he said in an address on state TV.
He steps down after 22 years in power.
Jammeh's successor Adama Barrow told a press conference, 'the rule of fear is over' as he prepares to return to The Gambian after being sworn in as president in neighbouring Senegal on Thursday and
Ghana is to deploy 205 soldiers to join the West African regional force to ensure the transition of power in The Gambia.
The Nigerian Air Force has already joined Senegalese troops on the border, who have said they are ready to enter the country if no political solution is reached by midnight.
A 90-day state of emergency has been declared in the country after its president of 22 years, Yahya Jammeh, has refused to hand over power after losing an election last year.
"The objective is to create an enabling environment ... [to] facilitate the inauguration of the President-Elect, Adama Barrow, on Thursday, January 19, 2017," Ghana's President Akufo-Addo said, referring to the winner of December's election.
The main opposition has said it is unhappy at the offer of asylum for Yahya Jammeh who had refused to step down as president.
Regional troops have secured the presidential palace in the Gambia's capital but there are fears the former leader has raided state coffers.
It ends a political standoff that briefly saw Yahya Jammeh and Adama Barrow claiming leadership of this tiny West African nation.