The Magpies have announced the 29-year-old has become their third January recruit following the arrival of Nabil Bentaleb and Valentino Lazaro.
Rose will be eligible to make his debut in Saturday’s Premier League game against Norwich at St James’ Park.
Rose told NUFC TV: “It’s a great honour for me to be here. I’m so grateful that the manager has brought me in and I’m looking to repay him in every way I can as soon as I’m playing.
“For me, it’s really exciting that I can come here and have the chance to play in front of the Newcastle fans.”
Squad number? 2️⃣8️⃣
Available for Saturday? ✅
— Newcastle United FC (@NUFC) January 30, 2020
Rose’s future at Spurs had been the subject of speculation for some time.
He has made only five appearances since Jose Mourinho was appointed manager in November.
He will bolster Newcastle boss Steve Bruce’s ranks following season-ending injuries to Paul Dummett and Jetro Willems.
Newcastle are thought to have beaten off competition from a number of clubs to secure Rose’s services.
Rose, who has also had loans at Watford, Peterborough, Bristol City and Sunderland in his career, said: “Newcastle is one of the biggest clubs in England.
“I spoke to the manager last night and he told me there were 50,000 fans here at the weekend against Oxford.
“You can’t go wrong with that kind of passion and support from the fans, and it’s something I’m looking forward to.”