Emotional King Charles was seen wiping away a tear during his mother's funeral.
The new monarch was visibly upset as the state ceremony took place at Westminster Abbey.
Leaders from around the world attended the moving ceremony, which is expected to be the most watched TV event in history.
The 73-year-old monarch led the procession, following Queen Elizabeth's coffin into the Abbey at 11am.
Senior members of the Royal Family looked solemn as they took their seats.
It is rare to see a member of the family display strong emotions, rarer so the monarch.
But Charles was seen crying in the ceremony this morning as the world gathers to lay the country's longest reigning monarch to rest.
Her Majesty's coffin laid on the blue catafalque draped in the Royal Standard flag with the Imperial State Crown, orb and sceptre placed atop.
Flowers with a card from Charles that read "In loving and devoted memory" were also placed on top of the coffin, which has been lying in state since Wednesday evening.
Releasing a statement of gratitude to the public last night, the King said he and Camilla had been "deeply touched" by the outpouring of grief.
"Over the last 10 days, my wife and I have been so deeply touched by the many messages of condolence and support we have received from this country and across the world," he said.
"In London, Edinburgh, Hillsborough and Cardiff we were moved beyond measure by everyone who took the trouble to come and pay their respects to the lifelong service of my dear mother, the late Queen.
"As we all prepare to say our last farewell, I wanted simply to take this opportunity to say thank you to all those countless people who have been such a support and comfort to my family and myself in this time of grief."
The Royal Family will lay Queen Elizabeth to rest today at St George's Chapel at Windsor, alongside her father George VI and beloved late husband, Phillip.
