The Mexican striker has joined Real Sociedad on a permanent deal after spending last season on loan with the Spanish side, bringing to an end a seven-year spell with the Gunners
The switch brings to an end to a seven-year stint in north London for the Mexican, where he scored 11 times in 62 appearances for the Gunners after making his first-team debut in 2008.
Vela scored 12 times in 35 matches last season for the Spanish outfit, and also contributed seven assists as Sociedad finished 12th in the Primera Division table.
The 23-year-old is believed to have signed a four-year deal at the club, and his first game as a permanent Sociedad player will come in the Liga clash with Barcelona on August 19.
Vela failed to break into the the Gunners starting XI, spending much of his time out on loan at clubs such as Osasuna and West Brom.