It's a significant selection because few countries are more discerning in assessing the qualities of first five-eighths, or flyhalves, as they are called in Wales, a country that produced Cliff Morgan, Barry John, Phil Bennett, genuine stars in the position.
Barrett will become New Zealand's 11th player to reach 100 Tests and the second five-eighths behind Dan Carter. He goes into the game having extended his world record of tries scored by a starting five-eighths to 26, of the 37 he has scored in all Tests.
Coach Ian Foster said Barrett had edged Richie Mo'unga for the start because he was playing well.
"He's been running this team the last couple of months, and so we felt he deserved the opportunity.
"It's his 100th Test, and he's in a good place to go and celebrate that with a game that means a lot to him. It's a big occasion here in Wales, he's on top of his game, so we're delighted with that selection.
"He's a quality person. The thing I love about him is he prepares the team first and then himself.
"He's selfless and on the field he's got that sense of adventure. He's his own style of 10, slightly different. He can do the stuff 10s do but he's also got the ability to add a bit of flavour to it as well with his running game and his speed. He's massively influential in our camp," he said.
Sharing the occasion will be TJ Perenara at halfback, his long-time Hurricanes teammate.
Foster said all the halfbacks were playing well, and while Perenara hadn't had his best 20 minutes in the US, they had been pleased with his overall game this year. Being the 11th Test of their year, it was also a case of using their resources in the right way, he said.
"We've gauged the energy and the enthusiasm and feel that TJ-Beaudy relationship has been a strong one for a number of years," he said.
Speaking to the choice of Rieko Ioane on the left wing, Foster said they had been delighted with him at both centre and wing this year.
"He's made some big strides forward this year and I'm sure you will see him at centre during this northern part of the tour. Right now we like the combination where Alby [Anton Lienert-Brown] has missed quite a bit of the last part of the Rugby Championship with a hamstring so we feel it is good for him to get some time," he said.
Jordy Barrett continued as the first-choice fullback, a reflection of the strong form he has shown this year.
"He brings a physical component to our back three, particularly up here at this time of year, it's wetter, the roof's open. We are expecting a pretty determined effort to get into our back three aerially and defensively and that's one of his strengths," he said.
In the loose forwards, Ethan Blackadder would start on the blindside flank. They had been delighted with his play as he had filled different roles but will have a chance to concentrate on his blindside role, Foster said.
He played well against the United States Eagles last week, and they felt he deserved to start again.