The group's decision to do so comes amid recent efforts by Republicans to defund the organization.
"Hillary Clinton holds the strongest record on reproductive rights of all presidential contenders in not just this election, but in American history," Planned Parenthood Action Fund, the political arm of the group, said in a statement. "She doesn’t just support women’s health — she has been a proactive leader on expanding access to women’s health care."
Clinton, who is pro-choice, has been a staunch supporter of Planned Parenthood and women’s health initiatives throughout her campaign.
“I will defend a woman’s right to choose, and I will defend planned parenthood,” Clinton has said in her stump speech on the campaign trail.
The news of the endorsement was first reported by CBS News.