Toral, who has an English mother was born in Reus, Spain and joined Barcelona’s youth team in 2003. The 20-year-old caught the eye at the Manchester United Premier Cup in 2010, a trophy he would win and moved to Arsenal with teammate Hector Bellerin in 2011.
The attacking midfielder featured in the 2012/13 NextGen Series and 2013/14 UEFA Youth League before breaking into the reserve team during the 2013/14 season.
Toral, joined Brentford on a season-long loan from Arsenal in August last year and made 36 total appearances scoring six goals.
The former Spanish U19 intemational scored a hat-trick against Blackpool in February, whilst also completing 90 minutes in Blues’ 1-0 home win over Brentford four days later.
Toral becomes Blues’ sixth summer signing joining Alex Jones, Jacques Maghoma, Adam Legzdins, Tomasz Kuszczak and Maikel Kieftenbeld.