She appeared after being subpoenaed by Republican lawmakers.
The hearing in front of the Committee on Education and Workforce focused on parental rights, school policies involving transgender students and federal education funding.
In her opening statement, she defended the focus on diversity in the district.
"The only way to truly serve a student is to understand and embrace what makes each student and community unique. By recognizing and responding to those differences we create schools where every student is seen, valued and supported," King said.
King testified alongside the superintendent of San Francisco's Unified School District, the superintendent of a Virginia county outside of Washington, D.C. and a leader at the National Center for Youth Law.