A dismal run of form has seen Sevilla lose four of their last seven LaLiga games and they sit just two points above the relegation zone.
Sampaoli's second spell at the club came to an end on Tuesday following a 2-0 defeat at Getafe, which proved the final straw.
The Argentine replaced Julen Lopetegui in October but managed just six wins out of 19 LaLiga matches in charge, although he did lead Sevilla into the Europa League quarter-finals.
Sevilla moved quickly to confirm a replacement, with former Real Valladolid, Alaves and Eibar boss Mendilibar drafted in on a contract until June 30.
His first match in charge will be after the international break, with Sevilla visiting fellow strugglers Cadiz. They then host Celta Vigo on April 7 before travelling to Old Trafford for the first leg of their Europa League quarter-final tie against Manchester United six days later.
Mendilibar has overseen 448 LaLiga games as a coach, winning 128 and losing 195.