Prosecutors recommended a four-month prison term for the actress, provided she doesn't appeal.
She appeared at a federal court in Boston yesterday holding her brother's hand and said nothing to reporters as she entered. Singer then facilitated cheating on Huffman's daughter's SAT test by having a proctor correct the teen's answers after the fact.
Huffman has apologized and said her daughter was unaware of her actions.
Sloane and Huffman join three other parents who have pleaded guilty so far in the scheme. Because she agreed to plead guilty, prosecutors said they would recommend four months in prison, but the judge could also choose not to put her behind bars at all. "Everything else they say I did, I did".
Assistant U.S. Attorney Eric Rosen recommended the four-month sentence, which was scheduled to be handed down September 13.
In a mea culpa a month earlier, Huffman said she would not contest the government's allegations and apologized to the public and her friends, family and daughter, who Huffman said knew nothing of the test-fixing scheme.
Huffman pleaded guilty alongside another parent charged in the case, California businessman Devin Sloane, who prosecutors said paid Singer 250,000 USA dollars to help his oldest son gain admission to USC as a purported water polo recruit.
Huffman is among 14 parents who have said they would plead guilty in the scam. He is accused of conspiring to bribe a University of Southern California athletic official to designate his son as a recruit for the USC water polo team, even though the son did not play the sport competitively.
Huffman, 56, admitted to paying $15,000 to correct answers on her daughter's SAT exam, a standardised test widely used for college admissions in the United States, leading to a remarkably improved score from the teen's Preliminary SAT performance, according to prosecutors.
Crying, Huffman, who is married to the actor William H. Macy, stressed that her daughter did not know about the crime.
"Yes, your honor", Huffman answered.
The couple pleaded not guilty in April to charges of fraud and money laundering on a "not guilty", so it now comes to a process. Prosecutors are seeking 1 year in prison for Sloane, who conspired to pay Singer $250,000 for his oldest son.
Investigators have said Macy, 69, was with her when admissions consultant Rick Singer explained how he could arrange for the cheating because he "controlled" a test center.