The State reported that 63-year-old John Fitzgerald O'Conner and his associate, 30-year-old Michael D. Shavo entered the pleas on Tuesday.
The Columbia men face 17 charges of conspiracy to launder money, commit mail fraud and mislead federal investigators.
Prosecutors say O'Connor, Shavo and Aiken attorney John W. Harte were involved in a fourth man's scheme where more than $5 million was stolen from an Aiken vending machine manufacturing company.
Prosecutors say Harte has pleaded guilty and will testify against O'Conner and Shavo.
The fourth man, 57-year-old William J. Trier II, was sentenced to about five years in prison on embezzlement and other charges in August.