The Queen and other members of the Royal Family stood to applaud a procession of bereaved families as they attended the 93rd Festival of Remembrance at the Royal Albert Hall.
The emotional moment came after the audience heard the story of Cyrus Thatcher, who lost his life in 2009 aged 19 while fighting as a rifleman in Afghanistan.
The Queen and the rest of the royal box joined the standing ovation as his parents, Helena Tym and Robin Thatcher, led a procession of bereaved families through the hall.
At the start of the event, crowds stood as the Queen, who is patron of the Royal British Legion (RBL) and the Duke of Edinburgh, entered the royal box overlooking the performance area.
They were joined on the left by the Prince of Wales and the Duchess of Cornwall, while the Duke and Duchess of Cambridge sat to their right, with other Royal Family members behind.
On either side of the Royal box were Prime Minister Theresa May and leader of the Opposition Jeremy Corbyn, who wore a poppy pin on his dark jacket.
They listened as old war songs including Take Me Back To Dear Old Blighty, It's A Long Way To Tipperary, and Pack Up Your Troubles opened the colourful show.
Other performances included Michael Ball and Alfie Boe who sang You'll Never Walk Alone, Laura Mvula's version of Abide With Me and Birdy's rendition of her song Wings.
Meanwhile, Alexander Armstrong, presenter of the BBC quiz show Pointless, filled the hall with his performance of Comin' In On A Wing And A Prayer, accompanied by the RAF Squadronaires band.
This year the event at the Royal Albert Hall marks the centenaries of the Battle of the Somme and the Battle of Jutland, the 25th anniversary of the Gulf War and the and the 80th anniversary of the first flight of the Supermarine Spitfire.
As part of the performance audience members were given wristbands which glowed in the dark, each one representing 100 of the 400,000-plus estimated British missing, dead or wounded during the bloody Somme offensive.
Also taking part was Nick Beighton, who lost both his legs above the knees in Afghanistan, and 11-year-old Beth Molyneux, whose Royal Navy father died when she was six, and who has wrote a poem about why she wears a poppy.
The Queen received a personal mention as, on her 90th year, she was thanked "for her unstinting service to duty and her unswerving commitment to the service of all her people".
Thousands of poppies fluttered to the ground from the hall's domed roof as the room observed a two-minute silence on the eve of Remembrance Sunday.
As the room turned to sing the National Anthem, the Queen waved her hand in acknowledgment before the service ended.