Regarded as one of the most destructive players in the southern hemisphere, Luatua has 15 international caps for New Zealand, recently touching down in the victory over Italy in November 2016.
Bristol today announced the 25 year-old would arrive ahead of the 2017/18 campaign.
"The signing of Steven — beating off competition from a number of high profile clubs — underlines the ambition of Bristol Rugby as well as Stephen Lansdown and the board's desire to drive us forward," Head Coach Mark Tainton told bristolrugby.co.uk.
"Since bursting onto the scene as a 19 year-old, Steven has been a consistently formidable presence, both at Super Rugby and for the All Blacks.
"He's a hungry, ambitious 25-year old and a standout performer at the very highest level — we're delighted to welcome him to Bristol Rugby and it's a massive acquisition for us."
Luatua, who can also play in the second row, has made over 60 Super Rugby appearances for the Blues.
"I have a fantastic relationship with Pat [Lam] and I enjoyed working with him at the Blues," Luatua said.
"I'm looking forward to taking on a new challenge with Bristol and contributing to the long term vision of the club.
"Bristol Rugby is one of the most ambitious clubs in the UK and that's backed up by a really passionate fan base. I've heard great things about the environment that is being built there and the plans in place, so I can't wait to get started in the summer."