In a section of the book, Harry discusses his distrust of the tabloid press and stories that circulated about him.
Opening up about the moment he found out he and Meghan Markle's move to the US had been leaked to the press, he wrote: "We got word from Sara that the Sun was about to run a story saying the Duke and Duchess of Sussex were stepping away from their royal duties to spend more time in Canada.
"A sad little man, the newspaper’s showbiz editor, was said to be the lead reporter on the story."
Watch: Prince Harry's memoir divides public opinion
The Sun's showbiz editor at the time was Dan Wootton who has since become a presenter on GB News and is a frequent critic of Harry and Meghan.
Harry added: "Why him? Why, of all people, the showbiz guy? Because lately he’d refashioned himself into some sort of quasi royal correspondent, largely on the strength of his secret relationship with one particularly close friend of Willy’s comms secretary – who fed him trivial (and mostly fake) gossip."
Ahead of the release of his autobiography, Harry has been critical of the UK press and its treatment of him and his wife.
In his interview with ITV's Tom Bradby on Sunday night, Harry also criticised the royal family for their lack of response to Jeremy Clarkson's controversial column where he said he "hated" Meghan Markle.
About the lack of official response from Buckingham Palace, Harry said: "The world is asking for some form of comment from the monarchy. But the silence is deafening. To put it mildly. Everything to do with my wife, after six years, they haven't said a single thing."
Harry also accused certain members of the royal family from having close relationships with sections of the tabloid press to improve their image.