Johnson has been outstanding for the Canaries this season.
He said: "It's great for my confidence to know the manager rates me and is picking me every week.
"It's probably one of the reasons I am playing the best football of my career.
"I'm very happy with the way it's going and at least it shows the manager has confidence in me!
"But I know I have to keep working hard and giving 100 percent if I want to hang on to the shirt."