The decision was taken in the wake of Saturday's 5-0 home drubbing by Real Madrid which left Betis five points adrift at the foot of the table.
Betis announced the decision on their website, saying they had a man lined up to take over.
"The club has decided to dispense with his services. The coach, who has not achieved the desired results, will not lead the team tomorrow. The intention of the board is that the new coach, who arrives tonight, will immediately take over the team.
"The club wishes to acknowledge the work and dedication of Juan Carlos Garrido and his staff during these months and wishes him luck for the future."
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