It was one of two transgender bills Little signed into law. Little also signed into law a bill that prohibits citizens from changing the gender on their birth certificate.
Left-wing activists reacted to the law's passage with indignation, and pledged to fight its implementation.
"We will continue to fight every day so that trans people have the same rights as every other Idahoan," the ACLU of Idaho said in a statement.
"Our country is facing an unprecedented health crisis, and Gov. Little and members of the Idaho Legislature have prioritized attacking transgender student athletes with this discriminatory and unnecessary new law," Rodrigo Heng-Lehtinen, deputy executive director for the National Center for Transgender Equality said in a statement.
Female athletes have expressed concern in recent years over the number of biological males competing in woman's sports. Former Olympic athlete Rebecca Dussault told the Daily Caller News Foundation last year that she believes every woman's sports record "will fall" if biological men are allowed to compete with women.
"I can tell you beyond a shadow of a doubt there are 1,500 men who on their bad day can beat Serena Williams in tennis," she said at the time. "There are 2,000 men who could outrun the fastest female sprinters of all time. So if one of them deciders to compete as a trans woman, there you go."
A poll conducted late last year found that just 29% of Americans support allowing biological men who identify as women to compete in women's sports.
Who is stealing trannies rights? No one! They've got UNCONSTITUTIONAL 'Affirmative Action' already going for them. Argh.