The decision by the Confederation of African Football also immediately stirred sporting controversy because Equatorial Guinea's national team was invited to participate as host despite being previously disqualified from the competition for cheating.
Equatorial Guinea is the late replacement for Morocco, which was stripped of hosting rights this week after asking for the tournament to be delayed over Ebola fears.
The country was praised Friday by the African Union for taking over the hosting duties of the 16-team tournament.
"(Ebola) should not paralyze continental programs and events," African Union Chairwoman Nkosazana Dlamini-Zuma said.
The Equatorial Guinea team, which was sanctioned in July for fielding an ineligible player in qualifying, and has previously forfeited World Cup qualifying games for the same offence, was reinstated as an automatic qualifier, CAF said.
Equatorial Guinea co-hosted the tournament with neighbour Gabon in 2012, when its human rights record under longtime president Teodoro Obiang Nguema also came under scrutiny.
The country agreed to step in at short notice and will hold the 2015 tournament on the planned dates of Jan. 17-Feb. 8 — part of CAF's requirements as the soccer body scrambled to find a replacement.
The agreement was struck Friday after a meeting between African football leader Issa Hayatou of Cameroon and President Obiang, CAF said.
"Following fraternal and fruitful discussions, the Head of State of Equatorial Guinea has agreed to host the tournament," CAF said in a statement. "Therefore, the Executive Committee of CAF confirms that the ... Africa Cup of Nations 2015 will be held in Equatorial Guinea on the dates agreed."
Obiang came to power through a military coup in 1979. During his leadership, U.S. authorities say top officials have amassed vast wealth through extortion, embezzlement and other corruption, while most of the country's 750,000 people live in poverty.
Obiang's son — who is also a vice-president of the country — was recently ordered to turn over $31.3 million in ill-gotten gains, which included a Malibu mansion, a Ferrari and Michael Jackson memorabilia like a "Thriller" jacket and crystal-covered glove.
Equatorial Guinea has also attracted criticism in football circles. Last year, Spain's national team was questioned for playing a friendly in Equatorial Guinea, and Obiang's regime was accused of using football to try to gain recognition and legitimacy.
At the 2012 African Cup, barely any of Equatorial Guinea's squad was born in the country, which appeared to be bringing in better players to try to boost its image. Equatorial Guinea, which had never before qualified for the tournament, made the quarterfinals.
For the 2015 African Cup, Equatorial Guinea will use four cities to host games: Malabo, Bata, Mongomo and Ebebiyin, CAF said.
Malabo — the capital which is located on an island off the mainland — and Bata hosted games in 2012 in newly-built stadiums. It was unclear what stadiums would be used in the other two cities as CAF didn't announce any other details on the venues.
CAF also announced the final draw for the tournament will take place in Malabo on Dec. 3.
CAF did not say which other countries it had considered as replacement hosts, but said "a few" African nations had shown interest in stepping in for Morocco. No other African country had publicly announced it was interested in hosting, however.
Gerald Imray is on Twitter at www.twitter.com/GeraldImrayAP