The 24-year-old has put pen to paper on a five-year deal at St. James’ Park.
Sels – who won the Professional Goalkeeper of the Year award in Belgium at the end of last season – joined Gent from Lierse in January 2014, and went on to make 106 appearances in all competitions for De Buffalos.
After helping Gent to the Jupiler Pro League title in 2014/15, Sels was called up to the senior Belgium squad ahead of their qualifiers with Andorra and Israel in October 2015, having previously represented his country at every age group from under-17 to under-21 level.
He brings European experience with him to St. James’ Park, having featured in the Champions League for Gent last season, and he arrives on Tyneside having kept 18 clean sheets during his final campaign at the Ghelamco Arena.
Rafa Benitez said: “I am really pleased to welcome Matz to the club. He’s a fantastic goalkeeper and many top clubs have been interested in signing him.
“Obviously we have injuries to Tim Krul and Rob Elliot which could be difficult for us in the first part of the season, so it was important to strengthen in this area to be sure we can make a strong start in the Championship.”
Sels added: “I’m very pleased – I’m very happy to be here. In Belgium, Newcastle is a really big club, and that’s why I chose Newcastle.
“As soon as Newcastle showed their interest in me, and I spoke to the coach, Rafa Benitez, it was an easy decision to make.”