Ayestaran, 59, rose to prominence as Rafa Benitez’s assistant at Valencia and Liverpool before falling out with the Spaniard, going on to take charge of teams including Maccabi Tel Aviv and, most recently, Portugal’s Tondela.
Following Emery to Villa Park will also be first-team coach Pablo Villanueva, who first worked with the manager at Sevilla and joined him in spells at Paris Saint-Germain, Arsenal and Sevilla.
Francisco Javier Garcia has been appointed goalkeeping coach with Antonio Rodríguez Saravia an individual performance coach. Victor Manuel Manas and Moises de Hoyo join as video/data analyst and strength and conditioning coach, respectively.
Manchester United await Emery’s Villa on Sunday for the ex-Arsenal coach’s return to the Premier League.
“My dream is to win a trophy with Aston Villa,” he said on Friday.
“It's my personal challenge at the beginning. My second dream, my objective will be to play in Europe."