Prince Harry revealed his and Meghan Markle's son Archie's first words were 'Grandma Diana'.
The Duke of Sussex said Archie has a photo of his late grandmother Princess Diana in his nursery.
In the documentary, The Me You Can't See, the 36-year-old spoke about his struggles after his mother died.
"I wish she could have met Meghan," he said about his mother. "I wish she was around for Archie.
"I've got a photo up in his nursery... and it was one of the first words that he said. Apart from 'mama', 'papa', it was then 'grandma', 'grandma Diana'."
He continued on the Apple TV+ interview: "It's the sweetest thing but at the same time makes me really sad."
Right after his brother Prince William, Prince Harry recently slammed BBC for using deceit to get their mum to give her bombshell 1995 Panorama interview.
Harry called out the "culture of exploitation and unethical practices" after a report into the interview, published today, concluded that journalist Martin Bashir acted inappropriately and in serious breach of BBC guidelines.
He described his mother as "an incredible woman who dedicated her life to service", describing her as "resilient, brave, and unquestionably honest".
In a statement, the Duke wrote: "The ripple effect of a culture of exploitation and unethical practices ultimately took her life."
Harry said that the finding was "the first step towards justice and truth" and praised those who had pursued the unethical practices.
Last night, William discussed his "indescribable sadness" at the BBC's failings in airing the programme which he said plagued Diana's "fear, paranoia and isolation".
The broadcast, watched by 20 million viewers, saw Diana admitting to an affair and claim "there were three of us in this marriage, so it was a bit crowded".
