The 28-year-old, who represented Tonga in last year's Rugby World Cup, will join the Exiles for the start of the 2012/13 season.
"Halani will be a strong addition to our front row as he is able to play on both sides of the scrum," said Irish head coach Toby Booth.
"He is dynamic and a good athlete which enables him to carry very well. His New Zealand upbringing means he displays good set piece attributes which is what we need in the Northern Hemisphere."
Aulika played for the Highlanders in the 2011 Super Rugby campaign and for Otago in New Zealand's domestic competition, scoring five tries.
"London Irish play a very expansive style of rugby that I am familiar with having played a similar style in New Zealand," said Aulika, who has won five caps for his country.
"I'm looking forward to the challenge of playing in the Aviva Premiership and testing myself against some of the best players in Europe."
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.
The All Blacks Performance t-shirt is black with hints of blue from the training jersey. Very Cool.
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The USA Rugby Pro Alternate rugby jersey is perfect for any fan of the Eagles. Get yours to wear during the summer Test matches.
The NEW All Blacks 2013/14 jersey has arrived at World Rugby Shop. Dare to wear the colors of the All Blacks.