Weah, 51, took over from Nobel laureate Ellen Johnson Sirleaf, who spent 12 years at the helm, steering the West African nation away from the trauma of a civil war.
He was sworn in as president by the chief justice of the Supreme Court, Francis Korkpor.
The ceremony took place at a packed sports stadium near the capital, Monrovia, with several African heads of state in attendance, along with friends and former colleagues from Weah’s football years.
Crowds queued for kilometres (miles) to reach the stadium, singing, dancing and waving the Liberian flag as they waited.
Weah has vowed to make prosperity and job creation the hallmarks of his presidency.
Liberia is one of the poorest countries in the world, ranking a mere 177th on the 188 countries in the Human Development Index compiled by the UN Development Programme.
