Kate Middleton, Prince William share Princess Charlotte portrait in celebration of her 9th birthday

Princess Charlotte is 9 years old.

On Thursday, Kate Middleton and Prince William took to social media to give their only daughter some special recognition on her birthday. 

"Happy 9th Birthday, Princess Charlotte!" the Instagram caption read, alongside a portrait of Charlotte taken by Middleton. "Thank you for all of the kind messages today."

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While it is unknown when and where the photo was taken...