William's school friend Fergus Boyd, childhood friend Hugh van Cutsem and Kate's Marlborough College friend Emilia d'Erlanger have been selected for the honour in the lead up to the christening of the third in line to Britain's throne here on October 23.
The Duke and Duchess of Cambridge, who have also opted for a relatively low-key ceremony in a break from tradition, decided not to pick any of the names from the usual list of royalty reportedly with the hope that George's godparents would help bring a sense of normality to his life.
Boyd, 31, is a partner at fund management firm Smith & Williamson who was in the same St Andrews hall of residence as the couple during their first year, and studied history of art with Kate.
The three moved into a flat together during their second year and have remained firm friends ever since.
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William is believed to have first shared his feelings for his future wife with Boyd.
D'Erlanger, also 31, co-founded London-based interior design company d'Erlanger and Sloan, and is a long-term friend of William as well as a schoolfriend of Kate.
"They are rather unexpected off-the-wall choices for godparents - not the usual suspects of William's closest friends who we anticipated. The two of them [William and Kate] have carefully chosen and agreed them together," a royal source told 'The Sunday Times'.
Van Cutsem is the best known of the three as one of William's oldest friends, with close links to the royals.
The Duke was an usher at the 39-year-old's wedding in 2005 to Rose Astor and is also godfather to their daughter Grace, who was a flower girl at the Kate and William's royal wedding in April 2011.
The guest list - although not yet officially announced - is also expected to cause some controversy, as it has been suggested that some key royals are among those who will not be invited as the couple wish to have an extremely "intimate" affair.