The 28-year-old was honoured with this role by Japanese coach Kenichi Yatsuhashi who took over last week ahead of the club's game against AS Vita Club in Caf Confederation Cup on Sunday.
Yahaya succeeds goalkeeper Joseph Addo who has experienced a dip in form recently.
"Yahaya Mohammed is our new captain and everyone at the club is happy with the decision," Oppong said.
"The new coach met the technical team, playing body and the club's top hierarchy and decided on the new direction. Everyone is aiming at the best for the club so we all agreed ahead of our game in Kinshasa next week," he added.
Yahaya also admitted that he is excited with the new role and promised to unite the team.
"I'm honoured with the decision and I believe things will be okay for us," he said.
"I've sought for the players' support and everyone wants to do away with selfishness or bitterness. All the players including the immediate past captain want to play their roles perfectly to help the club qualify out of the group in the Caf Confederation Cup. I want a united force to be able to achieve our target," he added.
Goal understands that former Medeama centre-back Paul Aidoo will named as deputy captain.