"At the end of the day I had a choice to make. I could have said 'no'."
She told the court that on one occasion while driving her daughter to a testing center she "thought to myself turn around... Just turnaround".
"And to my eternal shame, I didn't," Huffman said as she broke down.
While she spoke, her actor husband William H. Macy watched on from the front row, as his eyes welled up with tears.
Earlier, the star arrived at the court holding hands with Macy, as Huffman's brother followed the couple into the courthouse.
Huffman didn't speak to reporters on her way in. Macy has not been charged in the scheme.
Judge Indira Talwani said Huffman had "clearly accepted" the charges against her and that her previously clean record was factored into her sentencing.
Talwani said Huffman knew what she did was wrong.
"She knew it was a fraud it was not an impulsive act," the judge continued.
"Deep and Abiding shame"
Huffman paid $15,000 to boost her older daughter's SAT scores with the help of William "Rick" Singer, an admission consultant at the center of the scheme. Singer, who has pleaded guilty, allegedly bribed a test proctor to correct the teenager's answers.
Authorities said Huffman's daughter Sophia got a bump of 400 points from her earlier score on the PSAT, a practice version of the SAT.
The actress has said her daughter was unaware of the arrangement.
In a three-page letter filed last week with the federal court in Boston that is handling the bribery scandal, Huffman said she has "a deep and abiding shame" for her actions.
She said she has found motherhood to be "bewildering" and had turned to the scheme in the hopes of giving her oldest daughter a chance to pursue her dream of acting.
Huffman says in the letter that her daughter has a diagnosed learning disability and struggles with math.
"In my desperation to be a good mother, I talked myself into believing that all I was doing was giving my daughter a fair shot," Huffman wrote. "I see the irony in that statement now because what I have done is the opposite of fair. I have broken the law, deceived the educational community, betrayed my daughter, and failed my family."
Federal prosecutors wanted the judge to sentence Huffman to a month in jail for her role in a sweeping college admissions scheme, but the star and her lawyers pleaded for probation, community service and a fine instead.
In arguing for incarceration, Assistant US Attorney Eric Rosen said prosecutors had no reason to doubt the rationale Huffman offered - her fears and insecurities as a parent - for taking part in the scheme.
"But with all due respect to the defendant, welcome to parenthood," Rosen said. "Parenthood is terrifying, exhausting and stressful, but that's what every parent goes through...What parenthood does not do, it does not make you a felon, it does not make you cheat, in fact it makes you want to serve as a positive role model for your children."
Huffman's lawyer Martin Murphy argued that her crimes were less serious than those of her co-defendants, noting that she paid a low amount and that, unlike others, she did not enlist her daughter in the scheme.
"One of the key things the court should do is to impose a sentence that treats Huffman like other similarly situated defendants, not treat her more harshly because of her wealth and fame, or treat her more favorably because of her wealth and fame," Mr Murphy said.
US lawyer Andrew Lelling, meanwhile, argued that Huffman should spend 30 days in jail because she knew the scheme was wrong and participated anyway.
"Her efforts weren't driven by need or desperation, but by a sense of entitlement, or at least moral cluelessness, facilitated by wealth and insularity," his office wrote in its filing.
"Millions of parents send their kids to college every year. All of them care as much she does about their children's fortunes. But they don't buy fake SAT scores."
Huffman's husband said in his own letter to the judge that their family has struggled since his wife's arrest.
Huffman has rarely left the house and hasn't received an audition or job offer since her arrest six months ago, Macy said.
Their oldest daughter is taking a gap year and not attending college for now, Macy said. And the family, which also includes a younger daughter in high school, is also seeing a therapist together.
"Felicity's only interest now is figuring out how to make amends," Macy wrote, "and help her daughters heal and move on."
Huffman is among 51 people charged in a scheme in which prosecutors say wealthy parents paid an admissions consultant to bribe coaches and test administrators to help their children get into prestigious colleges.
The amount she paid is among the smaller bribes alleged in the scheme with some defendants accused of paying up to $500,000.
Over the next two months, nearly a dozen other parents are scheduled to be sentenced. Fifteen of them have pleaded guilty, while 19 are fighting the charges.
Among those contesting the charges are "Full House" actress Lori Loughlin and her fashion designer husband, Mossimo Giannulli, who are accused of paying to get their two daughters into the University of Southern California as fake athletes.
Former Stanford University sailing coach John Vandemoer is the only other person sentenced so far and received a day in prison. He admitted helping students get into Stanford as recruited athletes in exchange for $270,000 for his sailing program.