Name Clio
Gender Female
Homeland Kingdom of Corinthia
Race Human
Family King and Queen of Corinthia (parents)
Friends Princess Hildegard
Princess Amber
Princess Sofia
First Appeared Sofia the First: Once Upon a Princess

Princess Clio is one of the popular princesses at Royal Prep and is close friends with Amber and Hildegard. Her speaking voice is provided by Harley Graham, and her singing voice is provided by Jenna Lea Rosen, who also provides the singing voice for Princess Hildegard.

But Unlike Amber and Hildegard, Clio accepts Jade and Ruby more than they do, and the first one to admit how fun and nice Jade and Ruby are. She was even defending them at one point at the time when Jade and Ruby accidentally pushed over the chocolate milk fountain, and Amber's nightgown has a stain of the chocolate milk. At the time they were playing 'Pin the Tail on the Unicorn', Jade accidentally fell to the planets at the side and said she was the princess of venus laughing, including Clio.

In "The Shy Princess" when Flora announces the pairs for building a dream castle, she was paired up with Prince Hugo. It is revealed that she may have a deep crush on him (even after she saw him pull that stunt on Sofia in his debut), as when Flora announces "Clio and Hugo", she states, "aaaah" as if she thinks he is very dreamy.

In "Princess Butterfly"  she is the only one who sewed her leopard costume. Some of her spots fell off, But, Sofia said she did a great job.

Throughout the series, Clio has always done what Hildegard wanted because she said that's what best friends do. In "Sidekick Clio", it is shown that Clio didn't want to lose her friendship with Hildegard by doing things she liked. With some help from Sofia and Amber, Clio finally stood her ground and told Hildegard that she was going to audition for the school play because it was what she wanted to do. After winning the lead role and putting on a spectacular performance, she and Hildegard reconciled, with the latter realizing friendship works both ways. This marks the first time Clio wasn't submissive to others and may affect her in the future to be her own person. This is shown in "Lord of the Rink", when she chose to take ice dancing classes and Hildegard didn't.