Kairi is caring, kindhearted, and not afraid to speak her mind. However, she is determined and courageous when someone she cares about is in danger, often risking her own safety to help that person. In Kingdom Hearts II she becomes slightly more withdrawn because of Sora's absence, having obtained wisdom usually beyond someone of her age. She's not as brash and bold as she was in the first game, but is still sociable. Kairi also makes friends easily, quickly befriending Hayner, Pence, and Olette in Twilight Town before being kidnapped by Axel. She's usually always very cheerful and upbeat and seems to be bit of a tomboy as well. In contrast to Sora and Riku, who were both bothered by not knowing about Kairi's hometown, she took it in stride and was able to look at the positives about living in the Destiny Islands. She is loyal and headstrong, and she can be rather stubborn sometimes.

She has a gentle, high, girly voice and is originally voiced by Hayden Panettiere. Kairi's voice in this has to be a bit more mature than her KH1 voice.