Giving a speech to guests, Prince Harry opened with a moment of remembrance for the attack victims before fondly paying tribute to Prince Charles' "infectious" energy and enthusiasm for his charity work.
"It has certainly inspired William and I to get involved in issues we care passionately about and to do whatever we can to make a difference," he said.
He added: "Pa, while I know that you've asked that today not be about you, you must forgive me if I don't listen to you - much like when I was younger - and instead, I ask everyone here to say a huge thank you to you, for your incredible work over nearly 50 years."
During the speech, Meghan and the Duchess of Cornwall started laughing when a bee flew close to Prince Harry and he said: "That bee really got me."
The Duchess of Sussex's dusky pink dress is from British fashion brand Goat, which is often worn by the Duchess of Cambridge.
London-based milliner Philip Treacy is popular among the royals.