Brendon is coming as the reigning 24h Le Mans victor and he's also leading the current FIA LMP1 World Endurance Championship, which he won in 2015 as well.
The 27-year-old was rumoured to be in talks with the Italian F1 team but complications around his availability were also being factored in until the team announced this morning they had signed Hartley for the race.
Hartley becomes New Zealand's first Formula One driver since Mike Thackwell in 1984. He is part of a trio including fellow Kiwi Earl Bamber and German Timo Bernhard that leads the World Endurance Championship but will be looking for another drive next year after Porsche's decision to withdraw at the season's end.
Less than a year later he began providing testing in Mark Webber's place after the Aussie had suffered an injury, and for the 2009 season was the official reserve driver for both Red Bull and Toro Rosso. COTA is a track I really enjoy and one I have raced at recently.
The New Zealander will be a popular addition to the grid in Austin, an opportunity which would have seemed like an impossibly long shot just a few weeks ago.
He made no bones about his surprise at such a late call-up to the Red Bull F1 family.
Hartley says the years he missed out on F1 made him more determined to make this opportunity a reality.
We also reported that the list of potential one-off replacements for Gasly was vast, featuring Robert Kubica, Sergey Sirotkin, Sebastien Buemi and even Takuma Sato and Indycar champion Josef Newgarden.
He will join Daniil Kvyat in a revised line-up as Gasly returns to Japan to contest the Super Formula season finale. "In the early days walking down the road, he had to have a stride ahead of you", Smith said. However, the rumor goes that Kvyat threatened to quit Formula One and Toro Rosso should he not get his seat back.
"Brendon is coming as the reigning 24h Le Mans victor and he's also leading the current FIA LMP1 World Endurance Championship, which he won in 2015 as well", said Toro Rosso team boss Franz Tost. "With all the racing experience accumulated over the years, we are convinced that he will do a fantastic job for us".