Goalkeeper Matz Sels has joined the Magpies for £5m from Belgian club Gent.
The relegated club struggled between the posts last season with both Tim Krul and Rob Elliot missing time due to knee injuries.
“I am really pleased to welcome Matz to the club,” Benitez said. “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.”