The 34 year-old Finn moves to Toon after being released from Swansea City.
Manager Alan Pardew said: "We needed another option up front because we are a little light there due to the temporary loss of Shola, and Shefki will provide us with something different.
"He's match-fit and knows the English game well having been in the country for the best part of 10 years. He is ready straight away and that's what we wanted.
"Shefki is a good, honest pro who will give us a strong physical presence from the bench."
Kuqi is approaching 500 career appearances and 150 goals, many of them marked with his trademark "bellyflop" celebration.
He told Sky Sports News: "I don't really have the words to describe how happy I am. To get this chance is a massive thing for me.
"I am just happy to be here now and I can't wait to start and hopefully try to do the best I can for Newcastle United.
"For me, it is a great opportunity just to be back in the Premier League again. It is something I have tasted before.
"Everybody knows it is the best league in the world and to be part of it and a club the size of Newcastle United, I am really proud. It's an honour to be here."