Sawyer is to begin her new job Dec. 21. She is replacing Charles Gibson, who is retiring Dec. 18.
George Stephanopoulos is to replace Sawyer as "GMA" co-anchor alongside current co-host Robin Roberts, while Juju Chang is taking over as news anchor for Chris Cuomo, who is going to work for "20/20."
"And for one more time, Good Morning America," TVGuide.com quoted Sawyer as saying Friday morning. "This morning I am beaming at all of you. My heart is smiling, and the privilege of sharing my mornings with all of you has been more than I can say."