The Spanish goalkeeper was on the market, but his club's demands had so far been unrealistic for those who asked about him.
However, with the transfer window closing soon, Brentford's initial asking price was reduced to around £30 million - not a bad deal, considering Raya's contract expires next summer.
After attracting the attention of a number of Premier League clubs, the Spaniard decided he would not renew his contract with Brentford.
All things considered, the Bees are relatively happy to cash in on the goalkeeper.
Arsenal have signed a goalkeeper with a bigger reputation in England than in his homeland, but Raya has recently been called up by Spain.
The Spaniard will challenge Aaron Ramsdale for his established number-one spot, but manager Mikel Arteta will enjoy having such a problem.