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.
"I am ashamed of the pain I have caused my daughter, my family, my friends, my colleagues and the educational community.
"I want to apologise to them and, especially, I want to apologise to the students who work hard every day to get into college, and to their parents who make tremendous sacrifices to support their children and do so honestly."
She added in the statement that her daughter had known nothing about her actions: "In my misguided and profoundly wrong way, I have betrayed her. This transgression toward her and the public, I will carry for the rest of my life."