With nearly all ballots from Tuesday’s run-off vote counted, Mr Weah is well ahead of opponent Joseph Boakai with more than 60% of the vote.
As news of Mr Weah’s victory emerged, his supporters began celebrating in the capital Monrovia.
He will succeed Ellen Johnson Sirleaf, Africa’s first elected female president, in Liberia’s first democratic handover in decades.
“My fellow Liberians, I deeply feel the emotion of all the nation,” Mr Weah wrote on Twitter after the results were announced.
“I measure the importance and the responsibility of the immense task which I embrace today. Change is on.”
Weah starred at top-flight European football clubs Paris St-Germain (PSG) and AC Milan, before ending his career in England with brief stays at Chelsea and Manchester City.
He is the only African footballer to have won both Fifa World Player of the Year and the prestigious Ballon D’Or.
He entered politics after his retirement from the game in 2002 and is currently a senator in Liberia’s parliament.
Mrs Sirleaf defeated Mr Weah in the presidential election run-off in 2005 and took office a year later, after the end of a brutal civil war that saw President Charles Taylor forced out by rebels. Taylor is now serving a 50-year prison sentence in the UK for war crimes related to the conflict in neighbouring Sierra Leone.
This time Mr Weah’s campaign – under the Coalition for Democratic Change banner – appealed to the youth vote, while incumbent Vice-President Boakai was seen as old and out of touch.
But Mr Weah’s election is not without controversy, as his running mate was Jewel Taylor, former wife of the jailed president. (Courtesy BBC)