Gambians tore down posters of long-time president Yahya Jammeh and celebrated in the streets as the ruler of more than two decades conceded defeat in the election.
Mr Jammeh congratulated opposition coalition leader Adama Barrow, who won the most votes in the election that will remove him from power after 22 years.
Speaking on state television, Mr Jammeh praised the election and vowed not to contest the result.
Electoral commission chairman Alieu Momar Njie said Mr Barrow received 263,515 votes, Mr Jammeh won 212,099 and a third candidate, Mama Kandeh, received 102,969.
Mr Njie said: “Having received 263,515 I hereby declare Adama Barrow duly elected president of the Republic of Gambia for the next five years.”
Celebrations erupted in the streets of the capital Banjul, a normally sleepy seaside city whose white beaches lined with palm trees are a draw for European tourists. Gambians shouted: “We are free. We won’t be slaves of anyone”. Some waved the Gambian flag and opposition party signs.
Mr Jammeh had previously said that his “presidency and power are in the hands of Allah and only Allah can take it from me”, and on one occasion even said he would remain in office for “a billion years”.
After coming to power in 1994, he won a series of elections that were denounced by critics as rigged.
He is accused by rights groups of ordering the deaths of his political opponents and his regime has also targeted journalists, and homosexuals.
The announcement came a day after eight opposition parties united behind a single candidate – property developer Mr Barrow – to try to oust Mr Jammeh at the polls.
After voting on Thursday, Mr Jammeh had predicted “the biggest landslide in the history of the country”.
Mr Barrow said on voting day that he strongly believed Gambians were ready for change, adding: “He is not going to be re-elected – his era is finished.”
AP