U.S. talk show star Ellen DeGeneres arrived in Australia on Friday, declaring she was happy enough to "kiss the ground" as she began a six-day visit officials are hoping will help boost tourism.

Hundreds of cheering fans greeted the American wit after she touched down in Sydney, a moment she had earlier announced in a tweeted "made it to Australia" message written upside down.

DeGeneres, alongside her Australian wife Portia de Rossi, looked fresh as she emerged from the airport after initially delaying her arrival by several days due to flu.

"I'm feeling so much better," she told the Nine Network.

"I'd kiss the ground ... it's great to be here."

Greeted by the Qantas choir singing the "Men at Work" song "Down Under", DeGeneres stopped for an impromptu dance and chatted with fans at the airport.

When asked what she was most looking forward to, the Emmy-winning host said: "This would be enough for me but I can't wait to see everything."

Authorities hope her visit to Sydney and Melbourne will boost tourism, with the head of Destination New South Wales, Sandra Chipchase, saying the trip was a "golden" opportunity.

"She personifies Sydney. She's friendly, funny, witty and people love being with her," Chipchase said.

DeGeneres is expected to have a packed itinerary in Sydney which will likely include visits to the harbourside Taronga Zoo and iconic Bondi Beach as she films segments for her Ellen DeGeneres Show.

"I hope you're ready, Sydney!" she tweeted this week. "This Saturday I wanna meet you. Details coming soon!"

Before her journey on a Qantas plane renamed The Ellen DeGeneres Show Express, the host said she had been watching a documentary about Australia.

"Okay, I'm watching Crocodile Dundee, but I'm learning so much," she joked.

The visit has prompted police to warn fans not to get too carried away.

"Our message is clear -- enjoy the moment but consider other people, keep safe and listen to any direction of security or event staff and police," Detective Superintendent Anthony Bell told reporters.