De Jong will be on loan at St James' Park until the end of the season and could make his debut in Saturday's local derby against fierce rivals Sunderland.
"Newcastle is a great club and I have a good feeling about it," de Jong told the Newcastle website. "I am very impressed with the stadium and training ground and have been made to feel very welcome by everyone I have met.
"It has been a tough season for me so far, but I am here to play games and want to be important for the team, and successful with goals and assists. I am really looking forward to playing for Newcastle."
De Jong, whose older brother, Siem, plays for Ajax, rose to prominence with Dutch side FC Twente, scoring goals at a prolific rate between 2009 and 2012.
His form saw him included in the Netherlands squad at UEFA EURO 2012, but he failed to recapture his Twente form after joining Gladbach in July 2012.
"We're delighted to bring Luuk de Jong to the club," Newcastle's director of football, Joe Kinnear said.
"He has an excellent pedigree and will add significantly to our striking options."