Wearing a brown blazer with a white T-shirt that said "Free Slaves," Pinkett Smith told lawmakers that human trafficking is happening in our own backyard.
"Today, there are an estimated 27 million slaves worldwide, more than at any point in history. We call these men and women and children the victims of human trafficking. They represent every nationality, ethnicity, age group and they can be found everywhere, including here in the United States," she said.
The actress urged funding for programs that aid human trafficking victims.
"Fighting slavery doesn't cost a lot of money. The costs of allowing it to exist in our nation and abroad are much higher," she said. "It robs us of the thing we value most - our freedom."
Her husband, actor Will Smith, and their daughter, Willow, were also there for moral support.
Earlier this year, Pinkett Smith started the organization Don't Sell Bodies. The group's goal is to help bring about tougher laws against human trafficking, and it also offers support for victims.
The Associated Press contributed to this report.