Singer ran a steady business getting students into Yale, Stanford, Georgetown and the University of Southern California.
Both actresses were charged with conspiracy to commit mail fraud and honest services fraud.
Parents spent anywhere from $200,000 to $6.5 million to guarantee their children's admission to elite schools, authorities said.
USC President Wanda Austin addressed her university's involvement in a nationwide college admissions cheating, bribery and recruitment scheme.
Hollywood, college athletics and the academic world collided Tuesday when federal prosecutors charged almost 50 people in a scheme where college coaches and administrators were bribed by parents to help kids get into elite schools around the country. The allegations against actresses Lori Loughlin and Felicity Huffman provide insights into how these two alleged schemes worked.More news: Conor McGregor arrested in Miami on robbery, criminal mischief charges
Two famous Hollywood actresses, Lori Loughlin and Felicity Huffman, were charged in a MA court Tuesday along with more than 50 others for their alleged roles in an elaborate scam involving college admissions.
Huffman, who is married to actor William H. Macy, arranged for her daughter to be granted extra time for her SAT exam by having her certified as having a learning disability.
The Full House star's Instagram also went abruptly silent, with all of her posts first disappearing before the entire profile evaporated. Along with the parents, coaches and administrators of college entrance exams were also arrested.
"This case is about the widening corruption of elite college admissions through the steady application of wealth combined with fraud", Lelling said.
Wealthy parents paid Singer up to $75,000 for "someone to take the test for their child or correct the exam afterward", Lelling said.More news: Cohen sought Trump pardon, attorney says
The documents also allege that some defendants created fake athletic profiles for students to make them appear to be successful athletes.
Loughlin, best known for playing Aunt Becky on "Full House" and its Netflix sequel "Fuller House", allegedly paid $500,000 to have her two daughters with Mossimo clothing founder Mossimo Giannullli designated as recruits for the USC crew team, despite not actually participating in crew. The extensive court documents released on Tuesday noted Loughlin's payment to Singer was disguised as a "charitable contribution".
None of the students involved were charged as many were not aware of the scam, authorities said.
Singer, of Newport Beach, Calif., pleaded guilty Tuesday in U.S. District Court in Boston to charges including racketeering conspiracy and obstruction of justice.More news: Portland metro Saturday weather: Fog then the sun shines