Schweinsteiger last played for Germany in October 2013 before a string of injuries ruled him out for club and country.
"We all know how important he is for our game," Loew said. "He is a world class player who can make the difference for us in Brazil."
Schweinsteiger, who won his 100th cap against Sweden in October, is joined by versatile Borussia Dortmund defensive midfielder Kevin Grosskreutz, who last appeared for Germany in February 2011.
"With our sights set on the World Cup now is not the time for compromises and everything should be done with success in mind," Loew said in a statement.
"Many players, including key players, are still injured or just back from injuries and not yet in full form," Loew said.
"Now is the chance to act and find solutions and alternatives. That is why we brought some new faces."
Germany have been drawn to play Ghana, United States and Portugal in Group G at the World Cup.
Manuel Neuer (Bayern Munich), Roman Weidenfeller (Borussia Dortmund)
Defenders: Jerome Boateng (Bayern Munich), Matthias Ginter (Freiburg), Kevin Grosskreutz (Borussia Dortmund), Marcell Jansen (Hamburg SV), Philipp Lahm (Bayern Munich), Per Mertesacker (Arsenal) Marcel Schmelzer (Borussia Dortmund), Shkodran Mustafi (Sampdoria)
Midfielders: Lars Bender (Bayern Leverkusen), Mario Goetze (Bayern Munich), Andre Hahn (Augsburg), Toni Kroos (Bayern Munich), Mesut Ozil (Arsenal), Lukas Podolski (Arsenal), Sidney Sam (Bayer Leverksuen), Andre Schuerrle (Chelsea), Bastian Schweinsteiger (Bayern Munich)
Forwards: Pierre-Michel Lasogga (Hamburg SV), Miroslav Klose (Lazio)
- Sports & Recreation
- Borussia Dortmund
- Bayern Munich
- Pierre-Michel Lasogga