Tyree, who said in 2011 that he would trade in his famous Super Bowl helmet catch if it would prevent homosexuals from being married, will replace fellow former Giant Charles Way.
He also claimed that same year that "there is no specific evidence to support the claim of being born gay."
The HRC issued a statement Tuesday blasting the Giants for the decision to hire Tyree, stating that his claim "has been debunked and condemned by every major medical and mental health organization in the country, including the American Medical Association, the American Psychiatric Association, American Psychological Association, and many others."
"When did Tyree decide to be straight?" HRC president Chad Griffin asked in the statement. "The idea that someone can change their sexual orientation or gender identity is ludicrous, and the New York Giants are risking their credibility by hiring someone who publicly advocates this junk science. His opposition to basic legal equality aside, David Tyree's proselytizing of such dangerous practices goes against the positive work the Giants organization has done in recent years."
Despite the controversy, the Giants stand by their decision to hire Tyree, issuing a statement Tuesday evening that Tyree "was expressing his personal view, and that is not the view of the Giants organization."
New York Giants