"I am leaving my position as news anchor tomorrow," Cuomo said. "I have been blessed to be at 'GMA.' I thank all of you."
Cuomo will now anchor "20/20" with Elizabeth Vargas and continue on as a reporter for ABC News.
"It is a dream job for a journalist like me," Cuomo said. "But it was a very difficult decision because I'm leaving a special place and crew and all of you."
A network executive who spoke on condition of anonymity because the executive was not authorized to talk about hiring said Tuesday JuJu Chang has been offered Cuomo's current job as newsreader at "Good Morning America."
The personnel changes mean it's likely that George Stephanopoulos will be announced as Diane Sawyer's successor on "Good Morning America" within days.
The Associated Press contributed to this report.