The 27-year-old has 28 International caps to his name and is delighted to have finalised the move to Belfast after the world cup.
"I've been part of the Blues' family for my entire career so far and so, when the opportunity to look at a move came up, I felt that period post World Cup would be the perfect time," said Afoa.
"I've done my research and can't help but be impressed at how the Ulster Squad is developing. There's seems to be a good mix of local and overseas players and I'm very much looking forward to playing my part in that.
"I want to challenge myself and the northern hemisphere style of play will certainly offer me that. Most of the players moving north state that the chance to participate in the Heineken Cup as one of the key factors in their decision and the same is true for me, but since the possibility of a move came up I've also caught some of the Magners League and that looks like a competition that is going from strength to strength."
"From what I hear, the Ulster people seem to have a similar outlook as Kiwis and I've been told that I can expect a warm welcome when I arrive in Belfast. I have a young family who will be making the move with me and while the opportunity to experience a new culture and way of life will be a wonderful experience for all of us, it's nice to know that we won't feel too far away from home."
Ulster director of rugby David Humphreys, commented on the move:
"We have deliberately looked for high quality, international players in key positions and in John, we believe we've got it absolutely right"
"He's a hugely talented player, both at set piece and in the loose and he will bring a huge amount of Super Rugby and international experience to Ulster."