The contract is a one-year extension and Pontus' deal will now run until the end of the 2022/23 season.
The Swede, who will be 31 next month, has been ever-present at the heart of Brentford's defence in the Premier League this season. He has captained The Bees to six wins in 20 matches in the Club's first top-flight season since 1947.
Thomas Frank, Brentford FC Head Coach, said: “I am very pleased that Pontus has signed a new contract. He has been a big part of the success we have had over the last three years. He has been important to our defensive improvement in the last three seasons.
“Pontus has done well for us in the Premier League, and we are all pleased that he will be with us next season. His leadership and communication in defensive situations and his positioning are very important for us."