Valtteri Bottas has signed a new one-year contract with Mercedes to remain with the world champions until the end of 2018.
It means F1's three leading teams - Mercedes, Ferrari and Red Bull - will all have unchanged driver line-ups next season.
The Finn has impressed since replacing retired world champion Nico Rosberg at the Silver Arrows in January, claiming two wins - his first in Formula 1 - and seven more podium finishes.
The news means Bottas and Lewis Hamilton are set to remain team-mates for another year, but it leaves Mercedes with no drivers confirmed for 2019 - with the contract Hamilton signed in 2015 also running until the end of next season.
"I am honoured and proud to continue to work with Mercedes-AMG Petronas Motorsport in 2018 and to remain part of the Mercedes family," Bottas said.
"When the team hired me for the 2017 season, they took a leap of faith by putting their trust in my skills. This new contract for 2018 shows that I've earned that trust.
F1 in 2018: Driver line-ups and race dates
"I'm happy to have celebrated my first race wins in a Silver Arrow. However, there's always room for improvement and I still have not shown my full potential."
Mercedes boss Toto Wolff said: "We gave Valtteri a big challenge this year: 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. 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."
Bottas joined Mercedes following four seasons at Williams in which he had claimed nine podium finishes but never a race victory or pole position.
He broke his pole duck at April's Bahrain GP before taking his first victory at the Russian GP two weeks later, when he held off the challenge of Sebastian Vettel.
The 28-year-old claimed his second victory of the season in Austria while he has also finished second on four occasions, including in Azerbaijan where he came from last and a lap down to finish behind Daniel Ricciardo.
With seven Grands Prix remaining, Bottas is third in the Drivers' Championship, trailing leader Hamilton by 41 points and Vettel by 38.
Significantly, the dynamic between Bottas and Hamilton has remained harmonious so far, in stark contrast to the fractious relationship that developed between the Briton and Rosberg during their three years battling for the championship.
"He has earned his place and he will continue to grow," Hamilton said earlier in the season.
"He has done a great job, it's only his first year with the team. He will continue to go from strength to strength.
"Valtteri's energy is helping create a great harmony. When he is at the factory, he brings a great energy which everyone loves and appreciates."
Mercedes looking to 2019?
While Bottas rightly points out that he has "earned Mercedes' trust" with a solid debut season, the fact that he remains on a one-year contract points to a team keeping their options open.
Wolff expects to tie Hamilton down to a new contract, but Mercedes will surely be keeping an eye on what looks set to be an open driver transfer market in 2019.
Ricciardo's Red Bull contract is expiring, team-mate Max Verstappen is frustrated and has been openly praised by Mercedes in the past, while impressive Silver Arrows protege Esteban Ocon's two-year loan with Force India will be coming to an end. And that's not mentioning Vettel or Fernando Alonso.
All three of the leading teams keeping faith in their driver line-ups is a rarity in Formula 1, but with Ferrari possibly also on the lookout post-Kimi Raikkonen - 2019 could be a lot different.