Capped 31 times by his country and with seven test tries to his name, the 6 foot 3 star played in Scotland’s November tests against Wales, Fiji and Argentina.
Dunbar has made 92 Pro 14 appearances in his nine and a half seasons with Glasgow and a further 27 in the Champions Cup, director of rugby Dean Richards welcoming his arrival on Tyneside.
He said: “Alex is a very experienced operator at the top level who will help give us the strength and quality we need during the back half of the Gallagher Premiership season.
“He brings real physicality to the game, he picks great lines and he will offer us valuable competition in an important area of the side between now and the end of the season.”
Dunbar said: “Coming down to Newcastle for the rest of the season gives me a great opportunity to play some rugby, and I’m excited by the prospects here.
“I’ve trained with the squad today, everyone has been really welcoming and I’m just keen to get stuck in.
“I’ve watched a number of Newcastle’s games and they play an exciting brand of rugby, I know quite a few of the boys from the Scotland squad and this is a great chance for me to hopefully get some game time.
“The Gallagher Premiership is a really high-quality competition, I’ve been keen to test myself in that environment and it’s now just a case of trying to get up to speed with all the calls and patterns and pushing my case for selection.”
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