Looking forward to his time in Ireland, he said: "I'm really happy to be here. It's a challenge for me and I've met the boys, they're a great bunch of guys.
"They've been good to me and I'm looking forward to playing.
"I've heard that Connacht are seen as a bit of an 'underdog' side. But being the underdog is something that I relish and I'm looking forward to the challenge.
"I've always had a lot of pride in playing and I can't wait to get out on the field and get started."
Connacht team manager Tim Allnutt feels Ta'auso will be a major addition to the province's side.
"Niva is a very powerful, strong running centre. He's a linebreaker and a good distributor of the ball and we feel he'll improve our play in a crucial area," he said.
Ta'auso brings a wealth of experience with him to Connacht having previously played with the Waikato Chiefs before joining the Highlanders in 2007.
He has been capped 22 times in Super 14 competition and was also capped by the Junior All Blacks in 2006.