'It's A Difficult Day For Me'
Vieira took the co-host seat next to Matt Lauer five years ago, replacing Katie Couric. Vieira will be replaced by Ann Curry.
Meredith says she made the decision, "After months of personal reflection and private conversations with my family and friends."
She added, "I'm really sad because ... for the past 10 years this has been my second home."
Mererdith says she wanted to spend more time with her husband, Richard, and her kids.
Vieira -- who also hosts "Who Wants to Be a Millionaire" -- noted, "I really hope to stay with the NBC family ... that is my goal."
Lauer said Vieira "has brought class and dignity and talent and a joy of life to this show for the last five years."