Sopoaga is contracted for one final season with the Highlanders but the 16 test All Blacks first five-eighth is believed to have inked a two-and-a-half year agreement understood to be worth around £500,000 to 600,000 ($1.13 million NZD) per season.
Sopoaga has been signed as a marquee player which places his salary outside the cap.
It is understood he will not be available for the World Cup, robbing the All Blacks of their most established and experienced deputy to Beauden Barrett.
The 26-year-old out of Wellington College recently welcomed daughter Milla, and has clearly put the importance of securing his long-term financial future above representing the All Blacks.
He follows the likes of former All Blacks Charles Piutau and Steve Luatua to leave at the peak of his career.
No doubt the All Blacks will be frustrated with Sopoaga's move, having invested significant time into his development over the past three years, a period which includes two starts at No 10.
But, of course, every player has the right to decide their respective futures.
Sopoaga finished 2017 as the second ranked playmaker in New Zealand.
While there are no guarantees with Damian McKenzie shifting to No 10 with the Chiefs this year and Richie Mo'unga continuing his rise at the Crusaders, Sopoaga was near certain to attend the 2019 World Cup.
English newspaper The Times said the signing could encourage incumbent Wasps No 10 Danny Cipriani to leave the club.
It said Sopoaga’s decision was a "huge gain for Wasps" and a "significant loss for the All Blacks".
"He is the man around whom they will build their team for the next two years."
Attempts to reach the Highlanders were unsuccessful.