Former Arsenal boss Emery, who had been in charge of Spanish club Villarreal, will take over at Villa on 1 November.
Villa have paid a £5.2m buyout fee to Villarreal for the 50-year-old.
Caretaker Aaron Danks will again take charge at Newcastle this weekend, after Gerrard was dismissed last week following a 3-0 Premier League defeat by Fulham.
Emery, who would have been out of contract at Villarreal next summer, will begin work next week “after his work permit formalities are completed,” Villa said.
