Admiral Sir Tony Radakin said around 6,000 will form part of the procession and line the route in London and Windsor.
He said the planning has been going on “for a very long time”
Speaking about funeral plans, Admiral Sir Tony told the BBC’s Sunday With Laura Kuenssberg programme: “It’s enormous, it’s actually over 10,000 people in terms of both our soldiers, sailors and aviators, there will be about 6,000 as part of the procession and lining the route, both in London and Windsor.
“But it’s an enormous support effort as well. The planning has been going on for a very long time and we have the plans and now we have to execute them and there’s lots of brilliant people that are enabling that and it’s coming together as well.
“So the army the Royal Navy, the Air Force, but also our civil servants, and we’re helping other people in London, the emergency services, some of the volunteers as well, and so that this is a sombre occasion, but it’s done with the utmost respect and also the affection that I think is out there, and we want to represent the nation.”
Asked if he is nervous ahead of the service, Admiral Sir Tony went on: “There’s always an element of apprehension, but we have brilliant people that help at every level, some generals that have been planning this for a long time.
“We have warrant officers and non-commissioned officers that that look at the precise execution, and that’s at my level and then all the way down.”
He said all staff have been told to listen to a metronome at 75 beats per minute, “so that we get the right rhythm for the funeral procession”.
He said: “This is our last duty for Her Majesty The Queen, and it’s first prominent duty for His Majesty King Charles.
"We’re representing the nation. We’re representing our mothers, our grandmothers, our fathers, our friends, and everybody is very, very aware of that.”