The Desperate Housewives star said she had "betrayed" her daughter and was "ashamed" of the pain she had caused.
Ms Huffman is accused of paying $15,000 (£11,500) to have her daughter's exam questions covertly corrected in 2017.
The 56-year-old is one of 14 people set to plead guilty among the 50 charged, who include college athletic coaches.
In a statement, she said: "I am in full acceptance of my guilt, and with deep regret and shame over what I have done, I accept full responsibility for my actions and will accept the consequences that stem from those actions.
