Cobblers have been short on goals in recent weeks but the addition of the versatile Kanu should make a difference.
"Idris is a creative player who is direct, he can travel with the ball and he has pace," said Brady.
"He can be a threat at the top of the pitch or out wide and can play in more than one attacking position with the ability to create chances.
"He can be tricky to handle for defenders and he is an explosive player who can make things happen.
"Over the last 12 months he has had experience of both League One and the Championship and we think he will prove a good addition for us."