They appear as a couple on the popular reality television program broadcast by the cable channel Bravo.
In July they were charged in a 39-count indictment accusing them of conspiring to fraudulently obtain millions of dollars in mortgages and other loans, and of hiding assets and income during their bankruptcy proceedings.
Prosecutors also accused Joe Guidice of not filing federal tax returns from 2004 to 2008 despite an income of $1 million in that period.
The Guidices, of Montville, N.J., appeared composed during their court hearing and admitted their guilt before U.S. District Judge Esther Salas, the (Newark) Star-Ledger reported Tuesday.
They will be sentenced at a later date.