He started by asking for the wave from the front of the stage to the back. And as the British team received its medal, team captain David Henson led the 26,000-strong crowd in three cheers for the prince.
In the crowd were some of Harry's closest friends as well as ex-girlfriend Cressida Bonas and her pal cousin Princess Eugenie.
Harry started by reading a message from the woman he called "Granny," his grandmother Queen Elizabeth, who sent "warmest good wishes and congratulations to you all."
She praised how all the competitors "have used the power of sport to enhance your own recovery and to raise wider awareness of the enormous challenges faced by wounded veterans."
For his part, Harry said the games had "shone a spotlight on the unconquerable character of servicemen and women and their families – their Invictus spirit."
"These games have been about seeing guys sprinting for the finish line and then turning round to clap the last man in," he continued. "They have been about teammates choosing to cross the line together; not wanting to come second, but not wanting the other guys to, either. These games have shown the very best of the human spirit."
And he paused to remember those who could not be there.
"Many of us here this evening have friends who paid the ultimate sacrifice and are no longer with us," he said. "We want to take a moment to remember them."
Harry has said he'd like the games to continue – perhaps "up north," away from London next time. And he says that the USA has offered to host a contest in a few years.
Harry, who celebrates his 30th birthday Monday, was speaking after performances from pop and rock acts like royal family favorite Ellie Goulding (she sang at the 2011 wedding of Prince William and Kate) and singer-songwriter James Blunt and Canadian rocker Bryan Adams.
Harry ended his address looking at his speech, smiling and saying, "Crowd surf, question mark!"
And he introduced headline act the Foo Fighters, whom he'd met earlier in the week at a party at the U.S. ambassador's residence.
During the five-hour show, every competitor was given medallions, with Second Lady Dr. Jill Biden handing out the honors to the American team. The British armed forces team received its from doctors, nurses and specialists who help wounded warriors get over their injuries.