Saints have won all seven of their Super League games so far this season, and take on the Giants in the pick of the weekend’s fourth round ties.
Walmsley said: “It couldn’t have been a much tougher draw.
“Huddersfield were consistently the best team last year. In terms of the play-offs they probably didn’t do themselves justice but it’s going to be tough, it is a challenge we are relishing as a team and it’s going to be a great game, I am sure.
“You are not going to win the Challenge Cup final without beating some very good teams along the way. It’s a very tough first hurdle and it’s something that we are looking forward to testing ourselves with.
“We have played some very good teams this year already and every game has been tough on its own. Every team we have played has posed a massive test for us and fortunately we have managed to overcome those tests.”
The game at the John Smith’s Stadium will be televised live on the BBC, and immediately followed by the draw for the fifth round.