General Buhari was earlier accredited at the same polling unit early in the morning when accreditation started.
He is the strong opposition to the incumbent President and the presidential candidate of the Peoples Democratic Party, Goodluck Jonathan.
After voting, the APC Presidential candidate did not speak with reporters.
President Jonathan and his wife, Patience, were among the first voters to cast their votes in the state after voting started at about past 3:00pm.
He told reporters that he was hopeful.
Addressing reporters after casting his vote, President Jonathan urged Nigerians to be patient with the electoral body despite the issues with the card reader reported at some polling units.
After voting, President Jonathan said: “Let me again use this unique opportunity to congratulate our dear country Nigeria and everyone in Nigeria.
“We appreciate the patience of everyone.
“INEC wants to use the card reader to make sure that electoral process is credible and acceptable by international electoral observers. I believe that at the end of the day we all will be happy,” he said.