Diane Sawyer announced her last week on 'Good Morning America' Monday.
"I've calculated -- 2,881 shows," she said. "Roughly."
"I hope you celebrate with us this week, laugh with us this week," Sawyer continued.
Sawyer, 63, is taking over as "World News" anchor after Charles Gibson retires Dec. 18.
GMA co-anchor Robin Roberts called Sawyer's departure, "so difficult," adding that Sawyer is "my Thelma."
"It is amazing, I think to all of us, what we've been able to see you do on this show," co-anchor Chris Cuomo told Sawyer. "It makes us all proud."
Sawyer's colleagues are putting together video highlights of her biggest exclusives, including a 2006 interview with North Korean Gen. Ri Chan Bok, in which he warned that war was inevitable.