As part of a plea deal, Loughlin will likely serve two months in prison and Giannulli will serve five months.
She was released early as part of a policy regarding inmates who are set to be released on weekends, according to a prison official.
The charge accuses the parents of attempting to bribe officials at an organization that receives federal funding.
Parents Douglas Hodge, Michelle Janavs, Manuel Henriquez and Elizabeth Henriquez entered guilty pleas in Boston's federal court Monday after previously pleading not guilty. Each faces charges of money laundering and conspiracy to commit mail and wire fraud.
A judge has sentenced Felicity Huffman to 14 days in prison for her role in a sweeping college admissions bribery scandal.
Actresses Lori Loughlin and Felicity Huffman faced court appearances Wednesday on charges they took part in the college bribery scandal that has ensnared dozens of wealthy parents.