Jonker, who was compatriot Louis van Gaal's assistant until he was sacked last week, said 36-year-old Butt's experience was crucial as the German champions battle for a third-place finish and a spot in next season's Champions League qualifiers.
"I have to make sure we get into the Champions League and I think that we have more chances to do that with Butt," Jonker told reporters.
Butt, who twice before won back the No. 1 spot over then rival Michael Rensing, had been surprisingly dropped as first choice during the winter break with Van Gaal opting to start with youngster Thomas Kraft.
The 22-year-old initially delivered some solid performances but he has since faltered, gifting Nuremberg a second-half equaliser last week that saw Bayern drop back to fourth place.
With five matches to play, Bayern are on 52 points, one behind third-placed Hanover 96, while second-placed Leverkusen have 61. Borussia Dortmund lead the title race on 66.
Bayern president Uli Hoeness said days ago it was Van Gaal's insistence to push through his goalkeeping choice, despite being warned by the board, that greatly influenced their decision to part ways with the Dutchman after the 1-1 draw with Nuremberg.
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