The former England footballer, 41, was picked as the castaway for the landmark edition of the Radio 4 series, hosted by Kirsty Young.
In a clip released ahead of the broadcast, Beckham – whose fashion choices have included nail varnish, a sarong and a braided hairstyle – discusses his love of clothes.
Talking about being a page boy at a wedding, at the age of six, he says: "I had two options, just a normal suit or the option of burgundy, velvet knickerbockers with white tights and white ballet shoes, and I chose that, believe it or not.
David Beckham revealed to Kirsty Young, his greatest fashion moments
I felt great. My dad looked at me as if to say, 'really, is that what you picked?
"I felt great. My dad looked at me as if to say, 'really, is that what you picked?'.”
Asked if he ever wore the ensemble again, Beckham, who is married to Spice Girl turned fashion designer Victoria, says: "I think I did," to which Young jokes: "Not to football training, I hope!"
At the age of six, the footballer decked out in a burgundy suit for a wedding
Beckham adds: "I'm sure my mum has got that outfit at home."
The anniversary episode of Desert Island Discs will reintroduce sounds of the sea during the opening and closing of the programme, for the first time since the 1960s.
David Beckham in pictures
Thu, June 9, 2016
England football star turned model David Beckham's sexiest pictures
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Beckham's wife wife Victoria turned into a fashion designer, following the Spice Girls
Young has previously described Beckham as a "fascinating guest to welcome on to my little interview island".
The show is on BBC Radio 4 at 11.15am on Sunday