Tatupu is not eligible to join the Hawks' list until the end of 2013 but has agreed to a three-year contract following the draft, taking the 17-year-old through to the end of the 2016 season.
It follows the club's three-year deal with Kurt Heatherley, another athletic New Zealander, who has held an international scholarship at the club since the end of 2009.
AFL.com.au revealed in November the Hawks had committed to drafting Heatherley as an international rookie at the end of 2013. Heatherley and Tatupu were unveiled at the club's Ricoh Centre base on Tuesday.
Tatupu, who stands an imposing 197cm and 105kg, spent most of his youth playing rugby league and union. His father, Tony Tatupu, was a star rugby league player in New Zealand.
Graham Wright, the Hawks' recruiting and list manager, first saw Tatupu in Fiji during a tournament in 2009 as a 14-year-old.
He played for New Zealand in the 2011 Oceana Championships, and also took the eye for the South Pacific team in last year's NAB AFL Under-16 Championships in Sydney, where he was named his side's MVP.
"To be able to entice him to play AFL and commit to playing AFL was very exciting for us," Wright told AFL.com.au.
Tatupu will spend most of 2013 at home in Auckland finishing his studies, but will come to Melbourne during school holiday periods and travel to Europe with the AIS-AFL Academy squad.
He said the challenge of "trying something different" was behind his decision to pursue an AFL career, and he had already enjoyed learning off – and with – Heatherley.
"He's one of my best mates and I look up to him a fair bit and he's taught me a lot," Tatupu said.
"I love all the guys here, they all make me feel welcome, and watching them train is inspiring."
Heatherley spent the last two years as a boarder at Melbourne's Caulfield Grammar School after shelving a promising future in basketball and trying his hand at AFL.
Every Monday afternoon throughout the 2012 season he would spend a few hours at Hawthorn's headquarters working on the basics, while his game developed enough to play well at TAC Cup level for the Sandringham Dragons.
That's where Heatherley, a tall and quick defender, will spend most of 2013, although hip surgery will likely rule him out of action until late April or May.
"He just turned 16 when he came over to start and he's been amazing to move over to Australia by himself," Wright said.
"He's improved all the way through. He played as a full back with Sandringham and was very exciting in that role."
AFL national talent manager Kevin Sheehan praised the club for its vision.
"We congratulate Hawthorn on having the initiative to do it, to be the first club to move on this," Sheehan said.
"When we introduced the South Pacific into the under-16s championships three years ago we could see there's going to be potential emerge, and these are the first two boys to come through."
Callum Twomey is a reporter for the AFL website. Follow him on Twitter at @AFL_CalTwomey.
