The Duchess of Sussex has unveiled picture book The Bench, which is based on a poem she wrote for Prince Harry on his first Father's Day with son Archie, and tells the story of the father-son relationship as seen through the eyes of a mother.
Morgan wrote in his column in the MailOnline: "What would make the current shortlist for the title of World's Most Ludicrously Inappropriate Book?... Meghan Markle has written a book called The Bench about the very special bond between father and child.
Watch: Piers Morgan insists Princess Diana would be horrified by the divide between Harry and William
"Notwithstanding Ms Markle's seemingly unlimited thirst for committing attention-seeking acts of gargantuan hypocrisy, this seemed beyond parody."
He added: "Lest we forget, Ms Markle has ruthlessly disowned her father Thomas and refuses to have anything to do with him despite the fact they now live just 70 miles from each other."
The story – with pictures by award-winning Californian illustrator Christian Robinson – depicts a red-haired father in army uniform playing with his son while his mother watches through the window.
Meghan has said: "My hope is that The Bench resonates with every family, no matter the make-up, as much as it does with mine."
It will be published by Random House on 8 June, under the author credit Meghan, The Duchess Of Sussex.
Morgan takes issue with the use of this title, given that Meghan stepped down from royal duties when she and Prince Harry left the country last year.
The former Good Morning Britain presenter went on: "This new book about father-children relationships is just another example of Meghan Markle's never-ending penchant for preaching what she never practices...
"And if she really cared about father-child relationships, she would never have trashed Harry's family on global TV in the horrible way that she did, causing yet more damage, possibly irreparably, to Harry's relationship with his father."
Morgan, 56, quit the ITV breakfast show in March over comments he made about Meghan's interview with Oprah Winfrey.
Morgan's accusations that the Duchess of Sussex had been lying prompted thousands of complaints from viewers and broadcasting regulator Ofcom has launched an investigation.
Former actor Meghan, 39, married Prince Harry in 2018 and they had son Archie in May 2019. They are expecting a baby girl in the summer.
Watch: Meghan Markle has written a children's book