Roberts has given her time and resources to UNICEF as well as to other charitable organizations. In Spring 1995, Roberts, an enthusiastic supporter of UNICEF, asked if she could meet some of the relief agency's neediest recipients. On May 10, she arrived in Port-au-Prince, as she said, "to educate myself". The poverty she found was overwhelming. "My heart is just bursting", she said. UNICEF officials hoped that her six-day visit would trigger an outburst of giving: $10 million in aid was sought at the time[citation needed].

In 2000, Roberts narrated Silent Angels, a documentary about Rett syndrome, a neurodevelopmental disorder, which was shot in Los Angeles, Baltimore and New York. The documentary was designed to help raise public awareness about the disease. In July 2006, Earth Biofuels announced Roberts as a spokeswoman for the company and as chair of the company's newly formed Advisory Board promoting the use of renewable fuels.