Federal prosecutors in Chicago on Wednesday reached an agreement to drop felony corruption charges against Aaron Schock, the former Illinois congressman indicted in 2016 on charges that he misspent government and campaign funds.

In exchange, Mr. Schock, who was once seen as a rising star in the Republican Party, vowed to pay back taxes and reimburse his campaign.

“I am ready to put this behind me and move forward,” Mr. Schock said in a statement. “I have stated consistently and constantly that mistakes were made in the handling of my campaign and congressional offices, and I have acknowledged responsibility for that — but mistakes are not crimes.”

Mr. Schock resigned his House seat in March 2015 after he came under fire for lavish spending, including an opulent redesign of his Capitol Hill office that was reportedly inspired by a drawing room on “Downton Abbey.” It featured blood-red walls, a crystal chandelier and a plume of pheasant feathers. A Washington Post article about the renovation led to an investigation into whether Mr. Schock had improperly accepted pro bono interior design services. He later paid back $40,000.