In each of the state's 17 local government areas, Obi defeated rival party candidates.
At INEC's Enugu headquarters, the Enugu State Collation Officer, Dr Ofo Iweh, made the announcement on Monday.
Obi defeated PDP candidate Atiku Abubakar with a score of 428,640 to 15,747.
He said that APC received 4,772 points, APGA received 1,548, and NNPP received 1,808.
Prof. Iweh also revealed that a total of 468,891 ballots were cast, of which 456,424 were genuine and 12467 were rejected.