As a Mercedes young driver, Russell has long been suggested as the prime candidate to replace Valtteri Bottas at the Silver Arrows for next season.
But with a contract in place with Russell for 2021, the Briton has now declared he is to stay with Williams.
"I will be staying with Williams for 2021," said Russell, speaking in the FIA's Thursday drivers' press conference.
"I signed a three-year deal with Williams [ahead of the 2019 season], and I'll be staying there in 2021 to build off last year, and hopefully what this year turns out to be."
Asked if he felt disappointed with Mercedes for leaving him with Williams, Russell added: "No, I'm not disappointed in Mercedes at all.
"There was nothing more they could do. Claire [Williams, deputy team principal] was very firm with her decision, that she was not willing to, or not ready to let me go, and ultimately, as I have a contract with Williams, I have to respect that decision."
As a result of Russell's announcement, it is now incredibly unlikely Mercedes would elect to part ways with Bottas, with the Finn on a one-year rolling contract.
Nicholas Latifi has also confirmed his position with the team for next year, one he says will not be under threat even if the team has a change of ownership in the coming months,
"At the end of the day, I have a contract, so whether the ownership or anything changes going into next year, that shouldn't really be affected, so I'm just focusing on my job and we'll see what happens," said Canadian Latifi.
This year's only rookie in F1 added: "I have a multi-year deal with the team, so yes, I will be with the team in 2021."
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