The Stockholm-born right-back, who helped Sweden reach the quarter-finals at the 2018 World Cup in Russia, has signed an initial four-year contract at St. James' Park.
"We're pleased to bring him here," said Newcastle United's head coach Steve Bruce. "He turned 25 last week and has great experience, with more than 20 caps for Sweden and having played in the top flight in three different countries.
"He's a good height for a full-back, speaks excellent English and is a very good player. He's a really good acquisition."
Krafth becomes Newcastle's fourth signing of the summer so far, following Joelinton, Jetro Willems and Allan Saint-Maximin.
Speaking to NUFC TV, Krafth added: "It feels really good. It's been a busy couple of days, but finally I'm here. I'm very happy to sign for Newcastle and I can't wait to start training with the guys.
"When a Premier League team wants to sign you, of course you are happy. I know Newcastle is a big club, so I'm very happy to sign here and to be here right now.
"It's a good moment in my career to take a step forward. The plans Newcastle had for me, I felt like they was fitting me perfectly, so that was why I chose Newcastle."