Francis, who had earlier said he was innocent, pleaded guilty to charges of bribery and conspiracy in the case, which shook the Navy command structure when the investigation was made public last fall. He faces up to 25 years in prison.
As part of a deal reached with federal prosecutors, Francis and his company, Glenn Defense Marine Asia, will forfeit $35 million in property and other proceeds stemming from the alleged corruption. In addition to his own guilty plea, Francis also pleaded guilty on behalf of the firm.
The indictments alleged that Francis bribed Navy officers with cash, as well as prostitutes, high-end electronics, luxury hotel stays and high-priced entertainment for Navy officers who then shared classified information.
Francis, 50, allegedly received information on ship movements and schedules, and later on Navy investigations into his billing practices, prosecutors said.
Assistant US Attorney Mark Pletcher said the investigation in the case is ongoing, covering a ten-year period beginning in 2004.
Navy Captain Daniel Dusek also pleaded guilty to bribery on Thursday, bringing the total charged so far to eight, including two Navy commanders.
Prosecutors said Thursday that Dusek admitted that he used his position as Deputy Director of Operations for the 7th Fleet to help Francis.
"In return, Francis plied him with meals, alcohol, entertainment, gifts, dozens of nights at luxury hotels and the services of prostitutes," US Attorney Laura E. Duffy said in a statement on Thursday.
Dusek is the highest-ranking naval officer charged thus far in the case, she said.
Pletcher would not say whether more indictments are forthcoming, but hinted broadly that additional Navy personnel might be investigated.
"Francis maintained corrupt relations with scores of Navy officials," Pletcher added.
Of the eight people charged thus far, three including Francis worked with Glenn Defense Marine Asia and five are with the Navy.
The aftershocks of the scandal were felt high up in the Navy command.
Vice Admiral Ted Branch, director of Naval Intelligence, and Rear Admiral Bruce Loveless, director of Intelligence Operations, who have not been charged or accused in the case, have lost their access to classified information as the investigation continues, a Navy official said.