The service marked the first time the royal couples have been seen together in public since a family playdate at a polo match in July.
The event marks 75 years since notable battles of 1944, including Monte Cassino, Kohima and Imphal, D-Day and the collaboration of Commonwealth and Allied forces.
The service at the Royal Albert Hall was also attended by the Duke of York, the Earl and Countess of Wessex, the Princess Royal, the Duke and Duchess of Gloucester, the Duke of Kent and Vice Admiral Sir Tim Laurence.
Camilla looked elegant in a two-tone velvet dress with navy suede court shoes and one of her classic four-strand pearl chokers.
Prince William also wore a poppy, pinned onto his dark suit that was also adorned by two medals.
Both Meghan and Kate looked lovely with the Duchess of Sussex in a patterned black dress and her hair slicked back paired with Aquazzura pumps.
Another guest discussed the difficulty of deployment on military families, with the royal father praising the group as a 10-year Army vet himself.
The event is organised by the Royal British Legion, which provides assistance to United Kingdom military veterans and their families.
The ceremony will be hosted by the Royal British Legion, and commemorates all those who lost their lives in conflicts.
Last night's meeting was the first public engagement involving Kate and Meghan since a provocative ITV drama touched on their relationship.
The royals and baby Archie in South Africa earlier this year.
He admitted: "We're certainly on different paths at the moment, I'll always be there for him and as I know, he'll always be there for me". We will always be brothers.