Prince Louis joined his family - the Prince and Princess of Wales and siblings Prince George and Princess Charlotte - for the Coronation celebrations at Westminster Abbey and on the balcony at Buckingham Palace.
And the sweet five-year-old was spotted cheering on his grandfather in the royal carriage which took the family from Westminster Abbey to Buckingham Palace following the Coronation service.
According to lip reading expert Jacqui Press, who spoke to Femail, the young prince was saying: "'Yaaaay Say king. Yaaaay king." Later on, when Louis and the rest of the royal party arrived back at the Palace, the youngest of the Wales' children was spotted in an adorable moment with his older brother George, 9, during their balcony appearance.
The duo, who joined other members of the working royal family, their parents and the new King and Queen to wave to the crowds and watch the breath-taking flypast at the Palace, were seen chatting.
Read more on ok.co.uk