The Super Eagles defender has struggled to establish himself in the first team of the Championship team this season.
Ben Gibson and Dani Ayala were Karanka’s preferred pairing at the start of the year while Tomas Kalas got the nod on Tuesday night to partner Gibson against Millwall.
Omeruo has been involved, most recently at Sheffield Wednesday last weekend, but hasn't yet hot the heights this season.
Karanka, however, fully expects the Chelsea defender to come good and denies he’s suffering the after effects of his World Cup quest in Brazil.
“Both Tomas and Ben are playing really well,” said the Boro boss. “I am very pleased with Ken because he is a special player for me because he came here last season and he improved a lot.
“This season he is not at the same level and when you are not at your best level there are other players ready to play.
“But we have two months in front of us and all of the players are going to be very important.
“I hope Dani Ayala is with us as soon as possible so we arrive at the key moment in the season with the whole squad ready to play.”
“In the first game at home this season Ken came from the bench because Gibson got injured and he played without a warm-up and he was one of the best players so I don’t think that was the problem because he is strong," Kranka added.
“But he has to be at his best like the other players because if he is not at his best then I’ve got Tomas, who is now at his best, and Gibbo this season has been amazing, I am very pleased with him.”