The Andalusian side have started the domestic campaign with four defeats and just two wins from their eight games played so far.
Sevilla have also drawn their opening two Champions League games against Lens and PSV Eindhoven.
Mendilibar was named as the successor to Jorge Sampaoli back in March and helped guide Sevilla away from the relegation places and win their seventh Europa League title against AS Roma in May.
Sevilla currently lie 14th on the Spanish La Liga table following a hard fought 2-2 draw with Rayo Vallecano on Saturday.
A club statement read: "Following a meeting of the Club's Management Committee, Sevilla FC have decided to relieve Jose Luis Mendilibar of his duties as the club's head coach following the results at the start of the season.
"The club would like to thank the Basque coach for his services, whose role will go down in the Club's history after winning the UEFA Europa League in Budapest, the seventh time the club has won the tournament.
"Jose Luis Mendilibar was in the dugout for 28 official matches. This season, he has a record of two wins, five draws and four defeats. In the 2022/23 season, since taking charge of the team, he accumulated eight wins, six draws and three defeats between LaLiga and the Europa League.
"Sevilla FC wishes Jose Luis Mendilibar the best of luck for the future."
