The Hoffenheim full-back missed out as Low reduced his party for South Africa from 24 to 23 today. The coach had already seen his provisional squad reduced by injuries to Michael Ballack, Christian Trasch and Heiko Westermann.
Beck was informed of the decision by Low earlier today and was told he should remain on standby to fly out to South Africa in case Germany pick up any more injuries in Thursday's final warm-up game against Bosnia-Herzegovina in Frankfurt.
"[Beck] had an average season and was sometimes injured," Low said in Kicker. "We said to him that he should continue to feel part of the team. He is still young and will get his chance again in the national team."
Low added: "Of course it is disappointing for Beck. He has given a lot into our training camps and has always behaved fairly and correctly. He said a few words to the rest of the team at our meeting and they applauded him for that."
Beck, 23, has won seven caps for Germany, having made his debut in February last year. Bayern Munich's Holger Badstuber, 21, and Hamburg's Dennis Aogo, 23, who had not been capped before being named in Low's provisional squad, have been retained, along with all six strikers.
Germany are in a tricky-looking group in South Africa alongside Australia, Serbia and Ghana.
Germany's 23-man FIFA World Cup squad
Goalkeepers: Manuel Neuer (Schalke), Tim Wiese (Werder Bremen), Hans-Jorg Butt (Bayern Munich)
Defenders: Dennis Aogo (Hamburg), Holger Badstuber (Bayern Munich), Jerome Boateng (Hamburg), Arne Friedrich (Hertha Berlin), Marcell Jansen (Hamburg), Philipp Lahm (Bayern Munich), Per Mertesacker (Werder Bremen), Serdar Tasci (Stuttgart)
Midfielders: Sami Khedira (Stuttgart), Toni Kroos (Bayer Leverkusen), Marko Marin (Werder Bremen), Mesut Ozil (Werder Bremen), Bastian Schweinsteiger (Bayern Munich), Piotr Trochowski (Hamburg)
Forwards: Cacau (Stuttgart), Mario Gomez (Bayern Munich), Stefan Kiessling (Bayer Leverkusen), Miroslav Klose (Bayern Munich), Thomas Muller (Bayern Munich), Lukas Podolski (Cologne).
*Please note that squad lists only become official after they have been submitted to and announced by FIFA.