The Electoral Commission (EC) said the results were delayed because supporters of the two main political parties disrupted proceedings and asked police to clear collation centres.
Mahama’s supporters took to the streets to celebrate in the northern stronghold of Tamale, the central city of Kumasi and the capital Accra.
Bawumia said the statement was based on internal tallies by the ruling New Patriotic Party (NPP).
He said this showed Mahama had won “clearly” and the opposition National Democratic Congress (NDC) had also won the parliamentary elections.
Mahama confirmed that Bawumia had called to congratulate him on his “empowering victory”.
Earlier, the NDC said internal results showed Mahama garnering 56% of the votes while Bawumia got 41%.
The vice president said he would accept defeat before the results were officially announced “to avoid further tensions and maintain peace in our country.”
President Nana Akufo-Addo is resigning after reaching the official term limit of two terms.
Mahama, 65, previously led Ghana from 2012 to 2017, when he was replaced by Akufo-Addo. Mahama also lost the 2020 election, so this victory is a remarkable comeback.
Since the return of multi-party politics to Ghana in 1992, only candidates from the NDC or NPP have won the presidency.
No political party has been in power for more than two consecutive terms. This trend is expected to continue in the future.
Mahama’s previous tenure was marred by a slumping economy, frequent power outages and corruption scandals.
But Ghanaians are hoping things will be different this time.
Gajia One, an NDC supporter in Tamale, told the BBC: “We handed it over to them (NPP) and thought they could manage the country well, but they failed and we took over again.”
“John Mahama is the right person to rule this country. We are tired.”
Additional reporting by Natasha Booty
