Property developer Adama Barrow says his shock win of the Gambian election heralds new hope for the country.
Yahya Jammeh, an authoritarian president who ruled for 22 years, has confirmed he would step down.
"I will help him work towards the transition," Mr Jammeh said on state TV on Friday evening, after speaking to the president-elect by telephone.
Mr Barrow, 51, who has no history of political office, won Thursday's election with 45.5% of the vote.
Hundreds of Gambians took to the streets to celebrate the biggest upset in the West African country since Mr Jammeh took power in a bloodless coup in 1994.
Mr Jammeh has since ruled the country with an iron fist.
r Barrow won 263,515 votes (45.5%) in Thursday's election, while President Jammeh took 212,099 (36.7%). A third party candidate, Mama Kandeh, won 102,969 (17.8%).
The BBC's Umaru Fofana, who spoke to the president-elect, said he seemed bewildered by the result.
President Jammeh has congratulated the property developer and vowed not to contest the results after deciding "that I should take the backseat".
Have your say
More World Headlines
- 10 students die in suspected arson at Ugandan boarding school
- CNN sues Trump, top White House aides for barring Acosta
- California wildfires: Death toll reaches grim milestone
- Final school hostages freed in Cameroon
- Raging Californian fires kill 25
- Study finds 'huge' fall in FGM rates among African girls
- Trump, Macron may clash on European defense in Paris talks
- Death toll from Somalia hotel attack rises to 39
- Michelle Obama: I'll never forgive Trump for putting my family in danger
- 'Don't go back to school' kidnappers told freed Cameroonian students
- US proposes rule banning asylum for illegal migrants
- Ethiopia police find mass grave of 200 people
- At least 12 killed at California bar shooting
- Hundreds of buffaloes drown 'fleeing lions'
- Prince Charles wades into Jollof wars