What you need to know:
- Boakai was vice president from 2006 to 2018 to Ellen Johnson Sirleaf, Africa's first elected female president, who rebuilt the ravaged country after a civil war left an estimated 250,000 dead.
Joseph Boakai, who is expected to win the presidency in Liberia after incumbent leader George Weah conceded election defeat, has four decades of political experience behind him.
Boakai was vice president from 2006 to 2018 to Ellen Johnson Sirleaf, Africa's first elected female president, who rebuilt the ravaged country after a civil war left an estimated 250,000 dead.
This week's vote was Boakai's second run for the top job after he lost to President George Weah in a 2017 run-off.
The two faced off again in a second-round vote on Tuesday, following last month's hard-fought first ballot, in which neither secured an outright victory.
Boakai, 78, has castigated the record of his opponent, a former international star footballer, and emphasised his own experience in office, proposing a "rescue plan" for the West African country.
He has pledged to improve infrastructure, invest in agriculture, attract investment, open the country to tourism and restore Liberia's reputation.
"His motivation is to rescue Liberia from the current state it is in," Mohammed Ali, Boakai's Unity Party spokesman, told AFP ahead of the vote.
He highlighted an "influx of illicit drugs, the increase in the poverty rate (and) the image of the country being so low" as problems that have worsened under Weah's presidency.
His strategy seemed to have worked.
While six years ago Boakai won 28.8 percent in the first round and 38.5 percent in the second, he pulled level with Weah in this year's first round, with both receiving about 43 percent of the vote.
With almost all the polling stations tallied after the latest run-off, Boakai had garnered 50.89 percent of votes against Weah's 49.11 percent.
Boakai has promised an inclusive government, reflecting the country's political, ethnic, regional, religious and gender diversity.
Some of the 18 other candidates who were now out of the second-round race have endorsed him.
In the first round, he skillfully built alliances with local political leaders, such as the former warlord Prince Johnson, who supported Weah in 2017 and still enjoys strong support in his native Nimba County.
An ally of Johnson -- now a member of the Liberian Senate who is under US sanctions for corruption and was seen in a 1990 video sipping beer while his soldiers torture and kill president Samuel Doe -- is Boakai's running mate.
Their ticket won easily in the heavily populated northeastern region.
Like 57-year-old Weah, Boakai is from the Indigenous population and not the US-Liberian elite, who founded the free nation and were descended from slaves.
He was born in a remote village in Lofa County near the borders with Guinea and Sierra Leone, often called Liberia's "breadbasket".
He was agriculture minister from 1983 to 1985 under Doe.
Boakai portrays himself as a simple man who rose from humble origins through hard work. He is married with four children.
Age and credentials
Throughout the campaign, his team presented Boakai as a man of integrity whose credentials make him the only candidate able to tackle corruption -- one of Weah's key 2017 promises and one on which some voters say he has failed.
"He believes in perfection, he takes note of everything," his senior adviser Augustin Konneh told AFP.
"Boakai is a very humble person."
His opponents have argued that his age is a handicap, suggesting he is out of touch in a country where 60 percent of the population is under the age of 25.
Rather than aspiring to run the country, they say he should retire and have nicknamed him "Sleepy Joe".