Harry, 40, is suing News Group Newspapers (NGN), claiming that its journalists and private investigators unlawfully gained access to his personal information from 1996-2011.
The duke is expected to return to the UK to give evidence in person in February, the PA news agency understands.
The former Labour deputy leader, Lord Tom Watson, is also taking legal action against the publisher, which ran the now-defunct News Of The World as well as The Sun.
The trial before Justice Fancourt, which has twice been adjourned since the duke began the legal action in 2019, is due to last 10 weeks, with Harry expected to give evidence over several days.
NGN denies any unlawful activity took place at The Sun.
Several other high-profile figures have settled their cases against NGN, with 39 people settling claims between July and December.
In April actor Hugh Grant settled his legal claim after being advised he risked being liable for £10 million ($A20 million) in legal costs if his case proceeded to a trial.
Hugh Grant settled his legal claim instead of going to trial. (AP PHOTO)
Others who have settled cases include: actress Sienna Miller; ex-footballer Paul Gascoigne; comic Catherine Tate; radio presenter Chris Moyles; Spice Girl Melanie Chisholm; former Boyzone member Shane Lynch and actor Mathew Horne.
Speaking at The New York Times Dealbook Summit in December, Harry said he sought "truth and accountability" through legal action.
He said that 1300 people had settled their claims.
"They've settled because they've had to settle. So therefore, one of the main reasons for seeing this through is accountability, because I'm the last person that can actually achieve that."
He also said that he had become "professional" at litigation, but hoped "to retire fairly soon in that regard".
A spokesperson for NGN said in 2011 the company had published an apology to victims of voicemail interception by the News Of The World.
"The company publicly committed to paying financial compensation and since then has paid settlements to those with claims," the spokesperson said.
"In some cases, particularly those relating to The Sun, it has made commercial sense, and in accordance with common litigation practice, for the parties to come to a financial settlement without NGN accepting liability."
Two outstanding cases were now proceeding to trial and would be "fully defended".
Prince Harry's allegations of mobile-phone hacking had been struck out by the court so would not be part of the trial.
"His claim focuses now on allegations of unlawful information gathering by enquiry agents and alleged private investigators instructed by NGN journalists mainly in the early 2000s."
The trial is expected to begin on Tuesday.
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