Prosecutors in Wuppertal said that around 200 police officers and 50 officials searched British army premises in the towns of Moenchengladbach, Elmpt, Paderborn and Herford. Eight local companies were also examined.
German authorities suspect that some 21 civilian British military employees may have taken bribe money in return for contracts for work such as renovating and supplying army buildings.
A statement from the Wuppertal prosecutors' office said that payments may have also been made to non-existent shell companies for fake contracts, "costing the British government millions of euros."
The statement said British authorities were cooperating fully with German investigators, and that British military police had assisted with the raids.
The British military itself did not issue an immediate statement on the raids.