The actor and Oscar-winning screenwriter has traveled to the region three times in the last eight months -- and was accompanied on his most recent trip by "Nightline" producer Max Culhane and photographer Doug Vogt.
Affleck has visited refugee camps, hospitals, clinics and met with warlords, relief workers, child soldiers and members of parliament. He said he was trying to learn more about a place where more than 4 million people have died in a decade of fighting, disease and starvation.
"Congo is in terrible shape. What's going on here in this country is humanitarian disaster," Affleck said in a statement. "I think just helping people understand, that could have a real ripple effect down the road, and this piece will be one small incremental step in that."
Affleck's essay from the Congo is to air on "Nightline" Thursday.