The New York City lawmaker was set to be arraigned later today in federal court in Brooklyn.
Prosecutors didn't immediately specify the exact charges, but investigators have been examining his fundraising in a 2010 race and his involvement in a Manhattan restaurant.
A House of Representatives Ethics Committee announced in November that Grimm was under investigation for possible campaign finance violations.
Last week, Grimm's lawyer revealed that his client had been told by prosecutors that he would be charged.
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After the House Ethics Committee announced last fall that Grimm was under investigation, the panel said it would defer its inquiry because of a separate Department of Justice investigation.
Grimm made headlines in January after confronting a New York City cable news station reporter who tried to question him about a long-running FBI investigation into campaign finance while they were on a balcony in the Capitol.
During the 2010 race, Grimm acknowledged receiving USD 250,000 to USD 300,000 in contributions from followers of an Israeli rabbi, Yoshiyahu Yosef Pinto. Some members of Pinto's congregation subsequently said they made tens of thousands of dollars in illegal contributions, including gifts passed through straw donors.
Grimm has denied knowledge of any improprieties. The Israeli businessman who had served as Grimm's liaison to Pinto's followers, Ofer Biton, pleaded guilty in August to an immigration fraud charge.