Prince George Poses for the Most Adorable Royal Family Portrait -- See the Cute Pic!

The young prince posed with the other heirs to the British throne for Queen Elizabeth II's upcoming 90th birthday.

Prince George is just too cute!

The 2-year-old heir to the British throne posed for a new royal portrait in celebration of Queen Elizabeth II’s upcoming 90th birthday, standing on foam blocks for the photograph alongside his father, Prince William, his grandfather, Prince Charles, and his great-grandmother, the Queen herself, known to little George as “Gan-Gan.”

Royal Mail

WATCH: Prince George and Princess Charlotte Play in the Snow for First Time During Family Ski Trip

The portrait of the British heirs, which was taken last summer in the Drawing Room at Buckingham Palace by Ranald Mackechnie, has been released by the Royal Mail as a set of four, first-class stamps commemorating the Queen’s milestone birthday on April 21. It is the first time Prince George has appeared on a British stamp.

Royal Mail

WATCH: Prince George's First Day of Nursery School Makes Our Hearts Explode -- See the Pics!

There are also six more commemorative stamps celebrating the Queen public and personal life, including one with her father, King George VI, one with her husband, Prince Philip, and one with her children, Prince Charles and Princess Anne.

Royal Mail

WATCH: Kate Middleton Reveals Prince George Wants to be a Cadet Like Dad!

The stamps are available to pre-order beginning on April 20 on the Royal Mail’s website, and and available for purchase at 8,000 Post Offices around the U.K. beginning April 21.

See more about Prince George’s adorable relationship with his great-grandmother in the video below.

WATCH: Princess Kate Reveals Prince George's Adorable Nickname for the Queen