The 24-year-old had been the subject of interest from Huddersfield for a couple of weeks, with David Wagner seemingly admitting defeat at the start of the month as he rued the cost of English players.
But Wagner has now successfully bolstered his attacking ranks, with Pritchard - who joined Norwich from Tottenham in August 2016 - offering flair and versatility.
The former England Under-21 international is comfortable playing through the middle or on either flank and has notable ability on the ball.
Pritchard has signed a three-and-a-half-year deal, which Huddersfield have the option of extending by a further 12 months.
Bet we had you guessing! We're delighted to announce that @pritch_93 joins #htafc from @NorwichCityFC for an undisclosed fee, signing a three and a half year deal https://t.co/bRkfG5Jwkx (AT) pic.twitter.com/SQ30ClNv4U — Huddersfield Town (@htafcdotcom) January 12, 2018
"I'm very happy to be able to welcome Alex to Huddersfield Town," Wagner told the club's official website .
"He is exactly the type of player that we like to work with at this club. Alex is a young, British player who arrives as one of the top performers in the Championship and with a desire to prove himself in the Premier League.
"Now we will work hard with him to give him every possibility of being a success for us in the top division."
Pritchard - who is the club's second January signing after the loan acquisition of Terence Kongolo - could make his debut against West Ham on Saturday.