Opoku joins the Reds after his move to Serbian outfit FK Cukaricki fell through.
He is signed as replacement for Burkina Faso international Songne Yacouba who has refused to extend his contract with the club.
He bagged an impressive ten goals for Nkoranza Warriors in their Ghana Football Association Normalisation Committee Special Competition.
He has already commenced training with Kotoko where he scored five goals in their friendly win over Jachie Youth.