Ojo is in line to make his Bluebirds debut when they kick off their Championship campaign at home to Sheffield Wednesday at the weekend and the short-term move becomes the fifth of his Anfield career.
“I've got a point to prove and I'm really excited for the new challenge," Ojo told Cardiff's official website.
“Cardiff City is a massive club with great fans and great players – hopefully I can show what I can do here and fit right in.
"Wherever the ball is, I want to be involved in the game as much as possible.
“I'm delighted to get here in time for a full week's training with the team ahead of the first home game this Saturday. Now it's important that we start right."