The 19-year-old Slovenia Under-21 international is likely to be in the squad for Saturday's trip to Leicester.
Vuckic arrived on Tyneside in January 2009 and made the first of his five senior appearances this season against Fulham in August.
Speaking to www.cardiffcityfc.co.uk Vučkić said, "I'm excited and I can't wait to start playing for Cardiff City.
"I know that I'm on loan from Newcastle but I'm ready to play and give my best for the Club.
"The manager is a very good man and a nice person and I'm looking forward to playing for him. We're both very enthusiastic and I think we can work well.
"I came down to see the facilities on Thursday ahead of linking up with the other players for training on Friday morning. I like what I've seen - an excellent stadium with great facilities!"
The initial deal will see him at Cardiff City upto and including the away game at Bristol City. He is cup tied and will not be involved at Wembley for the Carling Cup Final.