In a statement, Red Bull said: 'The team will use the next nine races to evaluate Alex's performance in order to make an informed decision as to who will drive alongside Max in 2020'.
Albon - who was signed up to the Red Bull Junior Team in 2012 - has accrued 16 points in his maiden season in the championship with a best-placed sixth in the German Grand Prix.
The switch-around marks a meteoric rise for Albon, who was racing in Formula Two a year ago and seemed destined for a future with Nissan in the all-electric Formula E series before Red Bull stepped in.
The Dutchman did previously have a clause in his Red Bull contract which would allow him to leave the team if they did not meet certain performance criteria due to the new, untested partnership with Honda.
His demotion means Toro Rosso now have two drivers rejected by Red Bull, with Russian Daniil Kvyat also promoted and demoted and then dropped entirely before being given a second chance.
Arab coalition calls for ceasefire in Aden, Yemen
The government has said it will not negotiate with the separatists until they hand over all the military positions they seized. The commander was among 36 people killed - many of them newly graduated cadets - in the aerial attack, claimed by the Houthis.
'Everyone at Aston Martin Red Bull Racing looks forward to welcoming Alex to the team and supporting him during the next phase of his F1 career'. He sits in fifth place with 132 points, 69 points ahead of the 23-year-old Frenchman, and he has scored 75 points in the last six races alone.
Toro Rosso driver Alexander Albon of Thailand steers his vehicle during the second Formula One practice session at the Hockenheimring racetrack in Hockenheim, Germany, July 26, 2019.
In Formula 1's "silly season" rumours circulate about where drivers will end up the following campaign and beyond, and even the best drivers on the grid are not immune to the speculation.
Want your voice heard? Tune in to ESPN2's live broadcast of the 2019 Formula 1 season's 13th race, the Belgian Grand Prix, beginning at 9:05 a.m. ET from Circuit de Spa-Francorchamps on Sunday, September 1.