Maroney, 21, said she was abused over a seven-year period by Nassar.
Nassar is in prison awaiting trial in Michigan on multiple criminal sexual conduct charges and earlier this year admitted possessing child abuse images.
Maroney said the "unnecessary and disgusting" abuse started at a national-team training camp in Texas.
"It didn't end until I left the sport," she added.
But she was inspired to go public with her claims on Wednesday by others speaking out in the wake of separate allegations against Hollywood film producer Harvey Weinstein.
