She first wore it to the late monarch’s funeral back in September 2022.
The brooch is thought to have belonged to the Queen Mother, who was given it by Queen Mary in the 1920s, before being handed down to Queen Elizabeth II and then Charlotte.
According to jewellery experts, the brooch is estimated to cost £10,000.
Royal fans were quick to notice Charlotte’s sweet nod to the late monarch and took to social media to express their views.
One user wrote: “Love that Princess Charlotte is wearing the diamond horseshoe brooch.”
A second one added: “Princess Charlotte is wearing the diamond horseshoe brooch like she did during the late Queen’s funeral [heartface emoji].”
A third one said: “Oh wow! Charlotte got her own brooch as well Just lovely.”