The NSW government is promising a visit to Sydney by daytime chat queen Ellen DeGeneres will bring generous returns.

But it won't say how much it cost to get her here.

The US talk show giant has announced she will be bringing her top-rating show to Australia in March.

Film segments for The Ellen DeGeneres Show will be shot in Melbourne and Sydney to air in the US in April.

With DeGeneres' audience of more than 16 million, Qantas CEO Alan Joyce says the move is a "major coup" for Australia.

"This is a marketing opportunity that money can't buy," he told reporters in Sydney on Friday.

"The US market grew last year by four per cent but the UK market declined and that is because we have been very active with some of these marketing initiatives in the US market."

NSW Acting Premier Andrew Stoner said the government had financially backed the proposal but said the details were "commercial in confidence", describing it only as a "modest investment".

"We are confident ... that there will be a huge return for NSW," he said.

At a time when the industry has been struggling with a high Australian dollar, Mr Stoner said events like this were "worth every cent" and would drive increases in inbound tourists.

Following in the footsteps of Oprah Winfrey, who brought her show to Australia in 2010, DeGeneres - along with Australian actress Nicole Kidman - revealed the trip Down Under to her studio audience in the US.

During the in-studio announcement the audience learnt that they would be receiving 400 free return tickets, courtesy of Qantas.

Mr Joyce said he was expecting the DeGeneres visit would be "very different" from the Oprah experience.

"You don't want to just replicate things that have been done in the past," he said.