Alex Marquez will ride alongside his older brother and six-time MotoGP world champion Marc at Honda next season, the team announced on Monday.
The 23-year-old Alex Marquez, who added the Moto2 world title this year to the Moto3 crown he won in 2014, has signed a one-year deal with the constructors' champions.
"He will move from the intermediate class to partner eight-time world champion Marc Marquez in 2020 for his debut season in the premier class," Honda said in a statement.
The younger Marquez replaces three-time top-class world champion Jorge Lorenzo, who retired after the weekend's season-ending Valencia Grand Prix.
Alex has been riding for Kalex in Moto2 and won five races in the 2019 campaign, taking the title by three points from South African Brad Binder.
The announcement ends Frenchman Johann Zarco's hopes of joining Honda's top outfit.