And while it might seem likely that Kvyat will stay on, he has now been demoted twice by Red Bull - once from the senior team back to Toro Rosso in May 2016 and then dropped altogether after this year's Singapore event.
"What an wonderful feeling!" said Hartley, who will fill the seat temporarily vacated by France's Pierre Gasly. Hartley said in the official press release.
His elevation to a drive for Austin is further proof Toro Rosso is unconvinced about its line-up for next season.
Gasly was initially handed Daniil Kvyat's F1 auto for two races, Malaysia and Japan, however, Carlos Sainz's early move to Renault means he'll be staying with the team for the remainder of this season.
The drafting in of Hartley alongside Kvyat means Toro Rosso will field their third different driver line-up in 2017.
"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".