Though Lilibet and her brother Archie, two, didn't come along for the European visit, they were clearly at the front of their father's mind.
"I showed Archie a video of wheelchair basketball and rugby from the Invictus Games in Sydney, and he absolutely loved it," Harry told the outlet.
The royal, who established the games for injured service members in 2014, went on to say that he's already educating Archie on disabilities and mental health, two causes close to his heart.
WATCH: Prince Harry and Meghan, Duchess of Sussex's cute moment at the Invictus games. Story continues after video.
"I showed him how some were missing legs and explained that some had invisible injuries, too," he continued, adding that he "wanted to tell" Archie about these things.
"Kids understand so much, and to see it through his eyes was amazing because it's so unfiltered and honest."
Royal fans are eager for Harry to share more details about his children in his upcoming Today interview, with some even hoping that the Duke of Sussex will release new photos of them.
He and Meghan are notoriously careful about sharing photos of their children, having only ever released one image of Lilibet publicly.
However, the couple have allowed previously unseen images of Archie to be shown during several TV appearances over the past two years, including during their bombshell Oprah Winfrey interview and Meghan's solo appearance on The Ellen DeGeneres Show.
Harry's new interview will air in the US on April 20, but was filmed shortly after he and Meghan made a secret visit to the UK to meet with the Queen.
Few details about the visit have been released so far, though reports suggest that the three royals discussed plans for Her Majesty's upcoming Platinum Jubilee celebrations in June.
Multiple outlets have reported that the Queen has extended a formal invitation to the Duke and Duchess of Sussex – and their two children – to attend the festivities in London.
WATCH: Meghan Markle speaks at the NAACP Image Awards with Prince Harry. Story continues after video.
With speculation around their attendance rife, Harry may use the upcoming TV interview to share his and Meghan's Jubilee plans, which could include Lilibet's first meeting with the Queen.
Though she was named in honour of her great-grandmother (Lilibet was the Queen's childhood nickname), the 10-month-old has never met Her Majesty face to face.
That could change in June, with a possible return to the UK lining up perfectly with her first birthday on June 4.
This story originally appeared on our sister site, Now To Love.