The Basque trainer has agreed an 18-month contract with the Andalusians and will take charge of his side's Copa del Rey clash against Zaragoza on Wednesday.
Emery has been unemployed since he was sacked by Spartak Moscow in November following the Russian giant's humiliating 5-1 home defeat to arch-rival Dynamo.
Prior to his spell abroad, the 41-year-old made his name at Almeria, where he took the club to La Liga at the first time of asking in 2007, before guiding them to a ninth-placed finish in Spain's top flight a year later.
His work did not go unnoticed as Valencia named him as Ronald Koeman's successor in 2008, but despite finishing in a Champions League place in each of his four seasons, he was axed by Los Che in the summer.
Sevilla sits 12th in the table, having accumulated 24 points from 19 matches so far this term.