The ECI said its mission "is to help the Congolese people support local community-based approaches that create a sustainable and successful society in the long-troubled region."
Additional founding members include Howard G. Buffett, Humanity United, the Bridgeway Foundation and Jewish World Watch.
"The situation in eastern Congo has been neglected for far too long -- it is one of the worst humanitarian tragedies in the world," Affleck, who returned Monday from a five-day trip to the region, said in a statement. "I brought together this unique collection of partners in order to bring their experience in humanitarian relief and sustainable development to bear as we focus like never before on local solutions to challenges in this region. Right now, the attention paid to this crisis doesn't match the needs of those affected by it."
Faida Mitifu, the Ambassador of the Democratic Republic of the Congo to the United States and a member of ECI's advisory committee, said the Eastern Congo Initiative "will help to bring much-needed attention to a region that has suffered for too long."
"An approach that focuses on community-based solutions and highlights the vision of local organizations that serve those affected by conflict is essential," Mitifu said.
Affleck's film credits include "Good Will Hunting," "Armageddon," and "The Sum of All Fears."