The 23-year-old full-back has put pen to paper on a five-year-contract at St. James’ Park and becomes the ninth player to join the Magpies’ first team squad this summer.
Yedlin began his career at the University of Akron, in Ohio, before turning professional with Seattle Sounders in January 2013.
After 18 impressive months with the MLS side, he crossed the Atlantic to join Tottenham Hotspur but found game time hard to come by and spent the whole of last season out on loan at Sunderland.
A 39-cap international, Yedlin made his debut in February 2014 and had represented his country at the 2014 World Cup and 2016 Copa America.
“Newcastle is such a big and historic club, and I’m excited to have the honour of playing for them. Hopefully I can do great things here,” said Yedlin.
“I’m excited to learn under Rafa Benitez as well. He has an amazing résumé and I know he will help improve me a lot.
“I can’t wait to get started.”
Newcastle United manager Rafa Benitez added: “We have known for a little while of Watford’s interest in Daryl Janmaat, so it was important for us to bring in a replacement immediately.
“In DeAndre we have a player who knows English football well. He has good experience, an attacking mentality, ability and great pace.
“I think he can do really well for us and will give us good competition on the right.”