The 26-year-old flanker was part of the Samoa side which recorded a historic 32-23 win over Australia in Sydney's Olympic Stadium, last month.
Tu'ifua, who can also play at No.8, had only made his Test debut during the 34-15 win against Japan in Tokyo inJune - and has gone on to play him into contention for the World Cup.
Tu'ifua's form also attracted the interest of a number of clubs but it was the Falcons who moved the quickest to seal the deal.
"I'm absolutely ecstatic that he has decided to sign for us. We have been holding out to find this sort of player and we have finally got our man," said head coach Alan Tait.
"He's a big man, a good ball carrier and will give us so many dimensions to our set-up. He was a big part of the Samoan team which conquered Australia a fortnight ago and I am delighted that we held out for him," he added.
Despite the arrival of Tu'ifua bringing the number of summer signings to 14, Tait has confirmed he has not finished his recruitment yet.
"Everyone knows we are after a big centre but he has to be the right type of player," said Tait.
"We are again holding out for that player and hopefully we will get something tied up before the season starts."
Gilbert has released a new line of rugby cleats. The Gilbert Virtuo 8S is part of the exciting new product. Check it out.
The entire All Blacks apparel line has been updated for 2013/14. Check out the New Zealand All Blacks polo.
The Nike Tiempo is a solid rugby cleat and one of few styles still made from full-grain natural leather.
The Gilbert Blitz 8S rugby cleat is a great cleat at a great price of $69.99. Get a new pair of cleats today.
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Wear the crest of the British and Irish Lions on your t-shirt. A great look for the summer.
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The NEW All Blacks 2013/14 jersey has arrived at World Rugby Shop. Dare to wear the colors of the All Blacks.