Diane succeeds Charles Gibson who signed off his last World News broadcast Friday.
ABC News President David Westin said in a statement: "No one has come to the anchor chair on an evening news broadcast with more range or depth of experience than Diane."
Diane spent the day at ABC News World Headquarters in New York preparing for her first broadcast.
What you may not know is, Diane sawyer was born in Glasgow before moving to Louisville.
We went to her Barren County to find out what residents had to say.
Teresa Gillentine said: "It's great, her roots being tied down back to this area gives a lot of younger women, options in careers to look forward to and I think that's great."
And Tina Jewell said: "She had a dream, and she dreamt big and she got it. She moved to Louisville and now she has reached for the stars and she got it."