The 23-year-old, who has arrived on Tyneside for an undisclosed fee, expressed excitement at sealing a move and claimed his playing style is "suited to the Premier League"
The France international has arrived from Ligue 1 for an undisclosed fee and will wear the No.7 shirt with the Tyneside club.
And he was understandably "delighted" to complete the move, describing the Premier League as the best in the world.
He told the club's official website: "I am delighted to be a Newcastle United player.
"This is a massive club playing in the best league in the world, and I believe my style of play is suited to the Premier League.
"I have heard lots about how fantastic the Newcastle supporters are and cannot wait to get started.
"I am rising to a new challenge by coming here and want to firstly help the team improve this season and then progress after that."
Magpies manager Alan Pardew also hailed the latest of the club's numerous arrivals during the January transfer window.
"This transfer window has proved very productive for us and Moussa arriving today is a massive plus for the club," he said.
"He will bring drive and energy to the squad, he is a winner and that's why I'm especially pleased to have him with us.
"What all our signings this window bring is essential competition for places and that is great for the remainder of the season."