The Magpies have confirmed the capture of the Lille defender, who was a summer target, for a fee believed to be around 5 million pounds.
Newcastle United has completed the signing of French right back Mathieu Debuchy from Lille on a five-and-a-half-year deal.
The defender was believed to be close to joining the Premier League side during the summer transfer window following a string of impressive performances during France's Euro 2012 campaign, only for the two clubs to be unable to agree a fee.
Debuchy was present during Newcastle's 2-1 defeat to Everton on Wednesday as he watched from the stands at St James' Park, and joins up with fellow France internationals Hatem Ben Arfa and Yohan Cabaye after completing the 5 million pounds move.
"I hope I can bring something fresh to the team and help us get up to the highest possible position in the Premier League this season," Debuchy told the club’s official website. "I will give everything for this club."
Meanwhile, manager Alan Pardew admitted it was a "huge relief" to secure the long-term target's signature.
"It's no secret we've been trailing him for some time now and to have reached this point fills me with great excitement and anticipation in respect of what he will be able to offer the team," said the Newcastle manager.
He added, "At the same time it's a huge relief to actually have him with us now. He is an established top international player and it is a real coup for this club that we now have him at St James' Park."
"Mathieu will add real quality to our team, in terms of his ability, character and experience and I am sure he will quickly become a firm favourite among our fans too."
The right-back has 12 caps for his country so far, scoring one goal, whilst he won Ligue 1 and the Coupe de France with Lille in 2011.
The France international is expected to feature in Newcastle’s next Premier League fixture, against Norwich on January 12, however he will unavailable for Saturday’s FA Cup third-round tie away to Brighton.