Walcott played in each of England's friendly wins over Spain and Sweden at Wembley.
The pacy winger, though, feels whatever Arsenal side runs out at Carrow Road must not expect a walk in the park.
He told arsenal.com: "Norwich show tremendous spirit because they've got nothing to lose at times.
"Obviously they will be the underdogs going into the game, but we can't take that for granted.
"We have to be ready and on our game."