"I am. I am an alcoholic," Vargas said in a pre-taped interview that aired on "GMA" Friday.
"It took me a long time to admit that to myself. It took me a long time to admit it to my family, but I am," she said. "The amount of energy I expended keeping that secret and keeping this problem hidden from view was exhausting."
Vargas, 51, said her treatment was successful, she is now a member of Alcoholics Anonymous and is ready to return to the air Friday night on "20/20."