Zigi Shipper and Manfred Goldberg, 87, were sent to the Stutthof concentration camp near Gdansk in Poland by the Nazis when they were just 14.
The two men will share their experiences when the Royals visit Stutthof during the second day of their tour of Poland and Germany.
Mr Shipper and Mr Goldberg moved to the UK after World War Two and this will be the first time they have returned to the camp.
Speaking about his decision to go back, Mr Goldberg said: “For me it is quite a seismic event because, since I was permitted to come to England in September 1946, I have not set foot in either Germany or Poland.
“I decided that I really had to face the past and hence my consent to come.”
Describing the conditions in the camp, Mr Shipper said: “The weather I thought was going to kill me because it was like well below zero and you know we were wearing striped pyjamas because that’s what we got in Auschwitz.
“I never ever – except in Stutthof – thought that I was going to die.
“You saw people in front of you dying but I never thought I was going to die except in Stutthof.”
Like thousands of Jewish children and their families in the Second World War, Mr Shipper and Mr Goldberg were rounded up by the Nazis and forced into slave labour while living in the most inhumane conditions.
Mr Goldberg said they were regularly forced to watch public executions.
He said: “Jewish lives just did not count.
“We had to assemble in a square.
“They had erected an enormous gallows with eight nooses hanging down, then one by one we had to watch these innocent men being hanged.”
Around 110,000 people from 28 countries were imprisoned in Stutthof.
As many as 65,000, including 28,000 Jews died.
Mr Shipper and Mr Goldberg, who share their stories through the Holocaust Educational Trust, believe that close friendships kept them alive.
Mr Shipper said: “I said to my friends I can’t walk, they said they’ll help me, that was him and other people like that.
“Had it not been for them, I would not have been here today.
“I wouldn’t have survived.
“They said: ‘You know what will happen to you if you don’t walk – they will shoot you’.”
“I said: ‘But I can’t walk’, they said: ‘We’ll help you’.”
Mr Goldberg added: “If one of us got a bit more food than the other, we were able to share, live and let live, and generally give encouragement.
“That was probably the most vital aspect friendship in the camp, because none of us knew any morning whether we would still be alive that evening, quite literally life was a lottery.”