The midfielder was withdrawn after 58 minutes of Bayern's win at Borussia Dortmund at the weekend after hurting his left ankle and subsequently missed training on Monday.
While Bayern looked to allay fears he faced a lengthy absence, Pep Guardiola confirmed on Tuesday that the Germany captain would not be available at the BayArena.
"Schweinsteiger is definitely out," he explained, before adding there was no set date for Franck Ribery's return following an ankle problem.
With Schweinsteiger and Ribery missing along with Arjen Robben and David Alaba, Guardiola also dismissed suggestions his Bayern side would be significantly weakened for the last-eight clash.
"The injuries do not matter. We have many young players, we have 16 players who want to help the club and with them we will fly to Leverkusen," Guardiola added.
"It's a final. We have seen Bayer Leverkusen. They played very well in the Champions League and the Bundesliga. I admired this team from the beginning.
"We did not play well in Dortmund, but we won. The opposition was good but I am very proud of my team.
"The team must help Philipp Lahm. He is not at his normal level after four months out but he is always there and can help the team. Philipp is an example for me and for the team."
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