Bottas, who replaced defending world champion Nico Rosberg at Mercedes following his shock retirement, has won two races this year and heads into Sunday’s Singapore Grand Prix third in the standings, 41 points adrift of championship leader Hamilton.
The 28-year-old Finn has agreed a one-year deal, which allows Mercedes to keep their options open with Daniel Ricciardo and Max Verstappen both contracted at Red Bull until the end of 2018.
The 2017 Formula 1 grid
Hamilton’s deal with Mercedes also expires at the end of next year, but the Englishman is expected to sign a new long-term contract with the team.
Bottas, drafted in by Mercedes following Rosberg’s decision to walk away from the sport only five days after he won the championship, has steadily impressed in his opening year. The cool-headed Finn also provides the team with much-needed stability following three years of bitter in-fighting between Hamilton and Rosberg.
Mercedes non-executive chairman Niki Lauda revealed he had spoken to Sebastian Vettel about the German’s future plans, but following the announcement of his new three-year extension with Ferrari last month, Bottas was always likely to be retained.
“We gave Valtteri a big challenge this year by joining the team at the eleventh hour, stepping up to the forefront of F1 and pairing with the sport’s best driver as his team-mate,” Mercedes boss Toto Wolff said on Wednesday. “With that in mind, his results have been probably even more impressive.
“There have been ups and downs – more ups, fewer downs – and some great highlights like his two race wins in Russia and Austria. Overall, the balance of his performances and his upward trajectory made it a no-brainer for us to continue with him into 2018.
“For our team, the bonus factors are the respect and sportsmanship that have grown between our two drivers. The chemistry and dynamic between Valtteri and Lewis work and are what we need to take the fight to our competitors.”