The photo quickly garnered over 8,000 likes and many royal lovers commented on how they had never noticed the resemblance.
'Look at the lips in both of these pictures. Those are almost identical,' one wrote.
Another added, 'Oh, Princess Charlotte is so like her Grandma Princess Diana.'
One wrote, 'Charlotte is her mini me!' while another added 'Exactly the same!'
Another commented: 'I have been saying for a while now - Charlotte is going to look a lot more like Diana than anyone thinks...'
However, a lot of other fans think the little princess is looking more and more like her mother.
The adorable three-year-old stepped out to attend her little brother, Prince Louis', royal christening, and the Internet couldn't get over the young royals resemblance to her famous mum.
Rocking a sweet blue floral dress with matching shoes and headband, Charlotte once again stole the show.
However, despite many noticing the similarities between Charlotte and her mother and grandmother, the most noteworthy similarities that royal fans have picked up on is that of the three-year-old royal and her great-grandmother.