The 40-year-old was this week promoted from Villarreal's B team to replace Ernesto Valverde, who was sacked on Sunday after his side's 2-0 home defeat by Osasuna left the Yellow Submarine 10 points off the Champions League places in 10th.
Garrido has been at the club for 12 years in various capacities and has been put in charge until the end of the season.
He said: "For us it's an absolute final, because winning would give us a lot of confidence for future matches.
"The immediate results are key for the rest of the season. I'm going into the match with the highest hopes and knowing that I have a great team. If we win in Mallorca it would increase our motivation."