Shawcross replaced Steven Caulker with 17 minutes to go in Wednesday's 4-2 defeat - and was blamed for the second of Zlatan Ibrahimovic's four-goal haul.
Pulis said: "We are absolutely proud as punch that we have a player representing England.
"There hasn't been one at this club for a long time. It's a great fillip for everyone around the football club, and another feather in the cap for the club.
"I was disappointed he never started if I'm honest - I think he deserved to start.
"He was disappointed with the goal - I think he'll be the first to hold his hands up on that one. But he looked a little bit frozen when he came on - not mentally, but just a bit stiff."
Pulis, who takes his team to West Ham on Monday, claimed Shawcross would come out stronger after playing against a world-class player like Ibrahimovic, but admitted: "The lads have been caning him!
"Irrespective of who or what you are, if they think it's right to have a go at you they will, and he has got it in bucketloads today."