He defeated four other aspirants to win the ticket by polling 3,430 votes at the party’s national convention held at the Teslim Balogun Stadium, Lagos.
A former vice president, Atiku Abubakar, scored 954 votes while Governor Rabi’u Kwankwaso of Kano State got 974 votes.
Governor Rochas Okorocha scored 624 votes while the Publisher of Leadership Newspapers, Sam Nda-Isaiah, got 10 votes.
Sixteen votes were considered invalid and were therefore voided.
A total of 7,214 delegates were accredited to vote at the convention attended by the leaders of the opposition party.
Mr. Buhari, 72, was Nigeria’s military leader between December 31, 1983 and August 27, 1985.
With his victory, Mr. Buhari, a retired military general, will now face President Goodluck Jonathan, whose adoption was ratified by the Peoples Democratic Party, PDP, at its special convention in the early hours of Thursday, in the February 14 presidential election.
It would also be the fourth time the former military leader will be running for president. He lost in all three previous ones.
In 2003, Mr. Buhari contested on the platform of the defunct All Nigeria Peoples Party, ANPP, against former President Olusegun Obasanjo of the PDP.
He polled 12, 710,022 votes representing 32.17 per cent to Mr. Obasanjo’s 24,456,140 or 61.94 per cent.
In 2007, he ran again on the platform of the same party against the then outgoing governor of his home state, Katsina, Umaru Yar’Adua. He secured mere 6,605,299 votes or 18.72 per cent to Mr. Yar’Adua’s 26,638,063 or 69.82 per cent.
A few months after he and some of his loyalists dumped the ANPP to float a new party, the Congress for Progressive Congress, CPC, in 2011, Mr. Buhari threw his hat into the presidential ring again. He contested against Mr. Jonathan but polled 12, 214,853 to the president’s 22,495,187 votes.
The February 14 presidential election will therefore be a replay of the 2011 electoral battle as both Messrs Buhari and Jonathan will also feature again in the contest.