Winfrey yelled out her enthusiasm for Australia, saying she had been welcomed by open-hearted people as the crowd waved banners and flowers and blew kisses at the megastar who filled Melbourne's Federation Square to capacity.
The 56-year-old appeared on a stage with Prime Minister Julia Gillard, amid scenes reminiscent of the welcomes afforded to the Beatles and Abba in the 1960s and 1970s and Princess Diana in the 1980s.
"I don't know what it is with you guys, I was saying this to the prime minister, I don't know what it is, do y'all go to like friendly school? Everybody is so darn friendly," she said.
In a short speech to fans, some of whom had reportedly slept overnight in the square for a chance to see the American superstar, Winfrey said she was loving her first trip to Australia.
She described the country as "breathtaking", saying she had flown over the Great Barrier Reef, visited Uluru (Ayers Rock) in the country's desert heartland and had seen koalas mating.
"So I know, that is the definition of 'g'day mate'," she said.
Australian fanbase
In her only public appearance, Winfrey said she had decided to bring her show Down Under in its final season because of the support of Australian fans over the years.
"I love the fact that y'all have supported me and supported this show," she told the more than 8 000 screaming, applauding fans.
"When we looked around the world, our greatest fanbase was right here in Australia. So I said, let's go to the people who support you."
"Thank you Melbourne," she yelled.
Winfrey, who has brought 300 people from the United States as audience members for her only shows outside America, will film two episodes outside the Sydney Opera House, renamed the 'Oprah House' for the event, on December 14.
"This is one of the places I always wanted to visit," she said.
"I have to say, your country is simply breathtaking."
But speaking to her fans, she said that whether she was in Chicago or Melbourne people were ultimately the same.
"We are all in the deepest part of ourselves more alike than we are different," she said to screams of approval. "You have all proven that to me beyond a shadow of a doubt."
Plans to return
The talk show host said "I will be back."
Winfrey, who met with Aboriginal Australians while in the nation's desert heartland, said she was grateful for the hospitality she had received.
"I'm grateful to you for your hospitality. I'm grateful to you for your big open heart," she said.
"Can't wait to see how you live, how you love and how you par-tay," she hollered, before hugging Gillard.