"This means a lot to me," she said Friday night after winning the talk show award and telling her partner, actress Portia de Rossi, "I love you."
"Well, thank God, because it was either that or `Celebrity Fit Club,'" said O'Donnell, a former Emmy-winning daytime talk host.
Walters added, "We're so lucky to have her."
Vieira will become "Today" show co-host in September when Katie Couric moves to the "CBS Evening News."
For the first time in its 33-year history, the annual Daytime Emmy Awards ceremony was moved from New York to the Kodak Theatre in Hollywood, home of the Academy Awards. The ABC telecast also was expanded to three hours.
Former '80s teen idol Rick Springfield, who recently returned to "General Hospital" after 23 years, opened the show in an outdoor fan zone singing a medley of his hits before moving inside and concluded with "Jessie's Girl."
"Guiding Light" won four Daytime Emmys, including Kim Zimmer as lead actress. Zimmer won her fourth career trophy for a story line in which her character Reva Shayne Lewis went through menopause and eventually fell down an elevator shaft.
Before the show, Zimmer said that if she won she wouldn't allow herself to be nominated again after 10 nods. Backstage, though, Zimmer changed her mind, saying the only way she would withdraw her name was if other "Guiding Light" actresses stepped up to compete in the lead actress category.
"I'm at the end of my contract," she said. "Maybe the gods are intervening and saying you can't leave now. We'll see what happens."
The CBS soap opera also had a trio of first-time winners: Gina Tognoni for supporting actress, Tom Pelphrey as younger actor and Jordan Clarke for supporting actor.
"Oh my goodness, I didn't expect this," an exuberant Tognoni said.
"General Hospital" won for best drama and directing. The ABC soap opera has earned a record nine trophies in the drama category.
Tony Geary of "General Hospital" took home his fifth Daytime Emmy as lead actor. He first won in 1982.
CBS' "The Young and the Restless" topped the nominations list with 18, but its only trophy was for writing.
Jennifer Landon of "As the World Turns" won her first Emmy for younger actress. A year ago, the 22-year-old actress was a college student before getting her big break playing the scruffy Gwen.
"Oh boy, I have heartburn," said Landon, the daughter of the late Michael Landon of "Little House on the Prairie" fame, who never won an Emmy.
"To my Poppa, thank you," she said.
"Sesame Street" won for preschool children's series, making it 12-for-12 in the category.
"This is not too shabby for a show that's starting its 38th season," senior producer Carol-Lynn Parente said.
Caroll Spinney, the puppeteer who plays Big Bird and Oscar the Grouch on "Sesame Street," received the lifetime achievement award from the National Academy of Television Arts & Sciences.
Vieira of "Who Wants to Be a Millionaire" lost as game-show host, to Alex Trebek of "Jeopardy!" The quiz show was honored last week for game/audience participation show.
"I want to thank myself," Trebek said. "Forty-five years ago, I graduated from the University of Ottawa and had a few career opportunities available, but I chose television and I've never, ever regretted that decision."