According to the Sri Lanka's Elections Commission, Sirisena, a former Cabinet minister, received 51.28 percent of the votes in Thursday's election. His opponent, the current President of Sri Lanka Rajapaksa, collected 47.58 percent of votes. Rajapaksa conceded his defeat prior to the announcement of the final results.
Sirisena, 63, is set to be sworn in as Sri Lanka's new president Friday at 6:00 p.m. local time (12:30 GMT).
Sirisena used to be a close political ally of Rajapaksa. In December, he became the presidential candidate of the United National Party-led (UNP) opposition coalition.
UN Secretary General Ban Ki-moon has greeted the peaceful transition of power in Sri Lanka following the announcement of presidential elections results on Friday.
"The Secretary-General congratulates the people of Sri Lanka on the successful conclusion of the presidential election, and welcomes the constitutional transfer of power," Ban was quoted as saying in a statement.
Outgoing president Rajapaksa, 69, won presidential his first presidential election in 2005. After being reelected in January 2010, he amended the Constitution of Sri Lanka, removing the two consecutive term presidential restriction. In 2014, amid growing criticism of abuse of power, Rajapaksa declared snap elections, which he subsequently lost.
