"He's embracing his new life and everything is an adventure right now. He has moved on very quickly, and I don't think he misses his old life at all."
Royal expert Katie Nicholl wrote in Vanity Fair that Harry will likely be reflecting on his mum's life more than usual as he reaches this milestone.
He was 12 when Diana died in a car crash in Paris in 1997. On his 18th birthday he vowed he'd "carry on the things that she didn't quite finish" when it came to her charity work.
After quitting as senior royals in March, he moved to California with Meghan and their son Archie, where they now live in a multi-million dollar mansion in Santa Barbara.
Earlier this month, they announced a huge Netflix deal worth over $150 million, announcing their plans to "provide hope and inspiration" by producing documentaries, films and children's programming.
Nicholl wrote, "Harry's royal life is very different, but that pledge remains as important to him now as it was 18 years ago."
Scobie called it "destiny", saying, "We've long mourned Diana's place on the humanitarian landscape, and here we have Harry, who embodies her values and is willing to dedicate his life to them.
"He's at an age now where he's taken that baton and is able to run with it in a way that he would never have been able to do within the House of Windsor. That's very powerful and exciting."
Prince William and Kate Middleton shared a tribute to Harry on his birthday, just a month after claims of the brothers' broken relationship were published in Finding Freedom.
They shared a snap of Harry beating them in a running race in London in 2017, writing, "Wishing a very happy birthday to Prince Harry today!"
