Kate and other family members gathered at the Cenotaph to remember the soldiers who died in the war, but Queen Camilla was absent due to illness.
On November 10, the Princess of Wales appeared on the balcony above the Cenotaph War Memorial in London to attend the annual national Remembrance Day service held on the second Sunday of November every year.
Kate stands next to Sophie, Duchess of Edinburgh, on the central balcony.
Meanwhile, King Charles III and Prince William led the royal family in laying wreaths at the Cenotaph.
After flashing a smile and exchanging a few words with Sophie, Kate stood solemnly as the bells at Westminster Abbey rang at 11am, signaling the start of two minutes of silence.
Both royal brides wore black dresses and hats, and pinned three red poppies to their chests.
During her 13 years as a royal bride, Kate has never missed a ceremony honoring British and Commonwealth soldiers who died in war.
King Charles III appeared steadfast throughout the ceremony despite his cancer. His wife, Queen Camilla, was also ill . She had missed several events last week and was unable to attend the Remembrance Day service on medical advice because her condition was not improving. However, Camilla sent a wreath to the ceremony via her groom, Major Ollie Plunket.
The Prince of Wales, dressed in Royal Air Force uniform and holding a sword, raised his hand in a solemn salute during the ceremony.
After the wreath-laying ceremony and the singing of the national anthem, King Charles III led the royal family away from the Cenotaph.
On the balcony, the Duchess of Edinburgh also brought Kate inside. This was the second major event in a row that the Princess of Wales attended after completing chemotherapy. She is said to be gradually returning to the busy public life she had before her illness.