The 25-year-old is currently in the treatment room after sustaining a season-ending knee injury during training in February.
With his previous deal set to expire at the end of the season, Brentford had already agreed to fund his recovery even if the two parties failed to come to terms on a new contract.
However, the Premier League club have announced they have reached an agreement with Dasilva to extend his stay until next summer.
Dasilva signs new Brentford contract
The Arsenal academy product has put pen to paper on a new one-year contract which includes an option to extend by a further 12 months.
Brentford director of football Phil Giles told the club's website: "Josh has been so unlucky with injuries in recent seasons and hasn't played anything like the number of matches he'd have wanted to.
"This makes him and us even more determined to get him back to full health. He has shown amazing mental strength and resilience to take this latest setback in his stride.
"At his best, Josh is a very good Premier League player with attributes that are hard to find elsewhere. I'm sure he'll be back playing at some point in the 2024-25 season, and we can't wait for that to happen."
Two new contracts in as many days
Dasilva has struggled with hamstring, ankle and knee injuries this season, limiting him to just three substitute appearances in the Premier League.
In total, the midfielder has scored 22 goals and provided 12 assists in 157 matches since joining Brentford from Arsenal in 2018.
Brentford announced Dasilva's deal just one day after they confirmed Ben Mee had signed a one-year extension to keep him at the club until 2025.
Like Dasilva, Mee is also on the sidelines after sustaining an ankle injury at the end of February, bringing a premature end to his second campaign as a Brentford player.
Thomas Frank's side will wrap up the 2023-24 season when they welcome Newcastle United to the Gtech Community Stadium for Sunday's Premier League clash.