The judge had previously ruled in May that a claim by the actor Hugh Grant over alleged unlawful information gathering – other than allegations of phone hacking – can also go ahead to be tried next January.
Grant, 62, is suing NGN in relation to The Sun only, having previously settled a claim with the publisher in 2012 relating to the News of the World.
NGN has previously settled a number of claims since the phone hacking scandal broke at the News of the World, which closed in 2011, but has consistently denied unlawful information gathering took place at The Sun.
The judge’s ruling on Thursday follows the Duke’s high-profile court appearance last month in his lawsuit against Mirror Group Newspapers for alleged unlawful information gathering at the Mirror titles.
During the trial, lawyers for MGN accused the Duke of bringing the litigation “as a vehicle to seek to reform the British media” as part of his ongoing crusade.
In closing submissions, they argued that the Duke’s claim had “failed to withstand scrutiny” and that he had failed to identify any evidence.
Prince Harry has been involved in six legal battles at the High Court in recent months, three of which he has brought against British tabloid publishers over allegations of unlawful information gathering.
‘Significant victory for News Group Newspapers’
A spokesman for NGN said after the ruling: “The High Court has today, in a significant victory for News Group Newspapers, dismissed The Duke of Sussex’s phone hacking claims against both the News of the World and The Sun.
“As we reach the tail end of litigation, NGN is drawing a line under disputed matters, some of which date back more than 20 years ago.
“In arguing his case, the Duke of Sussex had alleged a ‘secret agreement’ existed between him/Buckingham Palace and NGN which stopped NGN from asserting that the duke’s claim had been brought too late.
“The Judge, Mr Justice Fancourt, found his claims in relation to the alleged ‘secret agreement’ were not plausible or credible. It is quite clear there was never any such agreement and it is only the Duke who has ever asserted there was.
“Mr Justice Fancourt then dismissed the duke’s phone hacking claims against both the News of the World and The Sun on the grounds that the claim had been brought too late.
“This substantially reduces the scope of his legal claim. The exact nature and scope of any trial of the remainder will be the subject of further hearings.”