Nonu, the 71-test All Black midfield back, announced yesterday he was joining the southern franchise, saying it was the best decision for him and his family.
He had signed a deal with the Blues last season and was expected to link with the Auckland-based team next season.
But he revealed yesterday he would turn his back on the Sir John Kirwan-coached side and come south.
"I have the utmost respect for JK and the Blues and it has got nothing to do with the Blues. This is a decision made for myself and my family," Nonu told a brief press conference in Christchurch yesterday.
He had talked to Kirwan last week but just felt the move south was the right one for him and his family.
Nonu was yet to sign a contract but was working through the details with the Highlanders and the New Zealand Rugby Union.
Highlanders coach Jamie Joseph said Nonu was a quality player and they did not become available too often.
But he sounded a note of caution over a backline with six All Blacks.
"It is a pretty exciting backline but you only have to look back to last year when we started with five guys injured in the backline.
"You never know what is around the corner," Joseph said.
"Everyone has talked about the Highlanders in the past couple of years starting off well and then falling away. That comes down to player depth being tested by injuries."
He felt the environment created by the Highlanders off the field had as much to do with clinching the Nonu deal as the playing stocks on the paddock.
"We put a lot of work into creating an environment that is positive for families. You find with pretty experienced rugby players that they enjoy their footy more by making sure their families are being looked after."
Nonu (30) has two children, and was believed to be keen to go back to Wellington but was not wanted by the Hurricanes.
He had friends in the Highlanders, such as Tamati Ellison and Hosea Gear, and Joseph had coached him in Wellington.
Veteran All Black lock Brad Thorn was also on the Highlanders' radar and was expected to link with the franchise by week's end.
Joseph admitted "when there was smoke there was fire" with regards to the Thorn signing.
Thorn, who will be 38 in February, was in the final year of a contract for Japanese club Fukuoka Sanix Blues.
With the signing of Thorn and Nonu and the earlier capture of All Black prop Tony Woodcock, the Highlanders could call on 12 past or present All Blacks for next season. Flanker Adam Thomson is yet to decide where he will play his rugby next year, but Joseph said the Highlanders were keen to have him.
The Highlanders finished eighth in 2011 and ninth this year, but expectations with a dozen All Blacks in the side will be considerably higher next season.
