Neuer hurt his right shoulder in Bayern Munich's 2-0 DFB Pokal final win over Borussia Dortmund on May 17.
Team manager Oliver Bierhoff said on Wednesday that Germany would be taking a cautious approach to his reintroduction, but it was confirmed by Bayern a day later that he had recommenced preparations for the FIFA World Cup finals.
The 28-year-old took part in a running session with his team-mates, but is not likely to be in contention for Sunday's friendly against Cameroon.
Neuer's Bayern team-mate Philipp Lahm also returned to training this week following a foot injury, while Bastian Schweinsteiger stepped up his comeback from a tendon problem.
Germany have been drawn in Group G for the 2014 FIFA World Cup alongside Portugal, Ghana and United States.
Joachim Low's side face Ghana in their Group G opener at Estadio Castelao in Fortaleza on June 21.
