Max Verstappen's co-manager says the new contract with Red Bull was negotiated "fairly quickly".
It is reported that the Dutch driver's salary has been doubled or even tripled as he ends speculation of a potential Mercedes switch with a deal through 2023.
"Max, Jos and I agreed fairly quickly that this was the best choice," said Raymond Vermeulen, who co-manages Verstappen with the 22-year-old's father Jos.
"We had the first non-committal conversation over dinner with Helmut (Marko) in Brazil," he told the Dutch publication Formule 1.
"Then it was a process. We held several internal discussions with each other about the short, medium and long-term vision."
Honda was a key part of the deal, as it is believed that the Verstappen camp has engineered an exit clause for if the Japanese manufacturer quits after 2021.
"We have every confidence about Honda's development," Vermeulen said.
"We think we have unfinished business with Red Bull and Honda. Red Bull helped us get into Formula 1 and we also have a fantastic commercial partnership, but the most important thing is to win.
"Max also feels like a fish in water with the team," he added.
