The former labour leader made the declaration in Abuja on Thursday.
He is expected to be the main challenger to the incumbent chairman, John Odigie-Oyegu if the latter decides to seek re-election.
Both men are from Edo State and are former governors of the state.
A meeting by APC state chairpersons and leaders in the South-south ended in acrimony due to the ambition of both men.
Mr Oshiomhole, however, enjoys the support of President Muhammadu Buhari. He is also believed to enjoy the support of a leader of the APC, Bola Tinubu; thus putting him in good stead to emerge chairman.