Dean Smith will be joined by long-term assistant Richard O’Kelly after an agreement was reached between Aston Villa and Brentford.
Smith was last week appointed as the successor to the sacked Steve Bruce at Villa, with former England and Chelsea defender John Terry named as assistant.
It is currently unclear what position O’Kelly will take, although he has been number two to Smith during their time together at Walsall and Brentford.
Phil Giles, co-director of football at Brentford, said on the club’s website: “The departure of Dean and Richard happened very quickly but they both left on good terms.
“We understood Dean’s desire to take the job at Villa and everyone knows his history at that club.
“He wanted to take Richard with him and we were able to reach an agreement.”