He and more than 100 other high-profile figures have brought a lawsuit against Mirror Group Newspapers.
Prince Harry will become the first British royal to appear in the witness box since the 1890s when he testifies at the High Court in London as part of his lawsuit against Mirror Group Newspapers (MGN).
Here are details of the trial:
What is the case about?
Harry and more than 100 other people are suing MGN – publisher of the Daily Mirror, the Sunday Mirror and the Sunday People tabloids – accusing them of widespread unlawful activities between 1991 and 2011.
Those involved include actors, athletes, celebrities and people who simply had a connection to high-profile figures.
They say the group’s journalists or private investigators carried out phone hacking on an “industrial scale”, obtained their private details by deception and carried out other illicit acts to find out information about them.
MGN is contesting the claims and denies senior figures were aware of wrongdoing. It also argues some of the lawsuits were brought too late.
Harry is due to give evidence when his specific case is heard over three days, starting on Monday.
What is phone hacking?
Phone hacking, the illegal interception of voicemails on mobile phones, first came to widespread attention in 2006 when the then-royal editor of Rupert Murdoch’s News of the World (NoW) tabloid and a private investigator were arrested.
They pleaded guilty and were jailed in 2007. The NoW and senior figures at the UK operation of Murdoch’s News Group Newspapers (NGN) said hacking was limited to a rogue reporter.
But further revelations in 2011, including that a murdered schoolgirl had been targeted, led to the closure of the paper and a criminal trial.
The Mirror group had consistently denied its journalists had been involved in hacking, including at a public inquiry, but in 2014 it admitted liability in four cases.
Since then, MGN has settled more than 600 claims at a cost of more than 100 million pounds ($120m) in damages and costs.
What is Harry saying about MGN?
Harry says 140 stories that appeared in MGN papers were the result of phone hacking or other unlawful behaviour. The trial is only considering 33 of these.
His lawyers said the intrusion led to the breakdown of his relationship with long-term girlfriend Chelsy Davy.
In other documents released at the outset of the trial, MGN admitted there was evidence that private investigators had been instructed to unlawfully gather information about three of those involved in the test cases, including, on one occasion, Harry.
The publisher said it unreservedly apologised and that he was entitled to compensation.
However, it has rejected his other claims.
Why is Harry taking action?
The MGN case is one of four that Harry is currently pursuing at the High Court against British newspapers.
He is also suing NGN over alleged phone hacking and other unlawful acts. NGN denies The Sun was involved in wrongdoing and is fighting to have his case thrown out.
The prince, with singer Elton John and five others, is also suing Associated Newspapers (ANL), publisher of the Daily Mail and Mail on Sunday, over phone hacking and illicit privacy breaches. ANL denies any unlawful activity.
Harry is also suing ANL for libel.