Harry, who was 12 when the accident that killed his mother happened, described Princess Diana as "the best mother in the world".
Before an audience of 500 invited guests at the Guards Chapel, he said that losing his mother was "indescribably shocking and sad".
"She made us and so many other people happy - may this be the way that she is remembered," he said at the end of his speech, drawing applause from the hundreds of members of the public who crowded outside the chapel.
Prince Charles' second wife, Camilla, with whom he had an affair while still married to Diana and whom Diana referred to as "The Rottweiler", did not attend the memorial service to avoid controversy, although she was invited.
Dubbed the "People's Princess" following her death, aged 36, Diana was adored by millions of people who never met her but who contrasted her charisma with what they viewed as a stuffy and hidebound royal family.
The emotional outpouring when she died led many commentators to question how long the monarchy might endure without her, but 10 years on it appears as solid an institution as ever.
|Diana died in a car crash in |
Paris in 1997 [AFP]
In a sign that perhaps, with hindsight, Britons feel that they may have overdone the grieving over Diana's death, a survey conducted by Sky News on Friday showed that 55 per cent of people thought the mourning had been excessive.
And in comments posted on the BBC's website, not all of the public was enamoured by the 10th anniversary service.
"For all those people still mourning the loss of Diana - has nothing happened in your life in the past 10 years that you still have to cling to her? I suggest you all have a reality check and get on with life," wrote Eliza in London.
Among the absentees at the service was Mohammed al-Fayed, the father of Diana's Egyptian boyfriend.
Al-Fayed, owner of the luxury London store Harrods, accuses Britain's royal family of ordering the couple's murder to prevent them from marrying.
Diana died in the early hours of August 31, 1997, alongside Dodi al-Fayed, following a crash in a tunnel.
Despite comprehensive police inquiries ruling out foul play, some Britons share al-Fayed's suspicions that the deaths were not an accident.
An official inquest into the deaths will begin on October 2, propelling Diana into the headlines once again.