The Senegal international is believed to have cost Alan Pardew's side around £10 million and signs a five-and-a-half-year contract at the Sports Direct Arena.
Cisse rose to prominence last season as he scored 22 goals in 32 Bundesliga matches as Freiburg managed a ninth placed finish, their highest final league position since 2001.
The 26-year-old will team-up with international team-mate Demba Ba at Newcastle once the duo return from the Africa Cup of Nations, with Cisse being given the iconic No.9 shirt formerly worn by Andy Carroll and Toon Army legend Alan Shearer before that.
Cisse, who had nine goals for Freiburg so far this season, spoke to Newcastle's official website about his move: "I would like to thank everybody for their welcome, and for inviting me to sign for the club. It is an honour to play for such a big club and I am looking forward to it.
"I want to pay back the confidence the Club have shown in me, and give the supporters something to be proud of.
"I am aware of the huge importance of the number nine shirt, and when I spoke with the manager he made it very clear how important this shirt is.
"I will treat it with the respect and I hope to do my very best in this shirt."
Cisse's new manager, Pardew, was also delighted by the signing with the former West Ham United boss relieved to have finally got his man after tracking him for a year.
"Ever since Andy Carroll left, Papiss was my first choice," declared Pardew.
"He is a finisher with an already-established CV in the Bundesliga, where we have monitored him for the best part of two years.
"Unfortunately he was out of reach, financially, for us in the summer, but it recently became apparent that Derek Llambias and Lee Charnley could do the deal in this window.
"In the short-term, of course, he is at the Africa Cup of Nations, but the competition he will bring to our squad when he joins up with us should inspire the players and reassure them of this club's ambition.
"Our fans know that this shirt brings its own pressures. One of the iconic numbers in world football - the number nine of Newcastle.
"It will be only fair that Papiss is given time to understand the responsibility it brings.
"As the manager, I wish him all the luck in the world to bring success to himself and this club."