Ni Hao, Kai-Lan

• Kai-Lan (voiced by Jade Lianna Peters) is a playful and adventurous 6-year-old Chinese-American girl and the host of the show with a big heart. During the show, she and her friends have to solve problems that come up during their daily life. Kai-Lan speaks both English and Mandarin Chinese. She can also translate the languages. She loves dinosaurs and hearts and she plays tambourine in her music group.
• Ye-Ye (voiced by Clem Cheung (English dialogue) and Ben Wang (Chinese dialogue)) is Kai-Lan's playful, thoughtful, and caring maternal grandfather legal guardian. He was born in Hong Kong and passes on his traditions to his granddaughter. He provides Kai-lan with gentle guidance, leading her to find her own answers, at her own pace. (Kai-Lan's parents and other grandparents are unknown.) He can play the tuba with surprises coming out of it like bubbles and confetti. He also enjoys picking apples and making dumplings for Kai-Lan and all her animal friends. He's known to pop out of places unexpectedly, but the friends are always happy about it.
• Rintoo (voiced by Jack Samson) is a rambunctious and energetic yellow 6-year-old Bengal tiger with a frontal lisp accent. Sometimes, Rintoo acts before he thinks and problems in the show happen to him more. Even if he's with Hoho most of the time like for favorites and problems, his actual best friend is Tolee besides Kai-Lan. He loves dragons and race cars and in Kai-Lan's music group, he plays xylophone.
• Tolee (voiced by Khamani Griffin) is a 5-year-old gray koala who loves pandas and fruit (especially apples, bananas, and pineapples). He is intelligent and always thinks before he acts and sometimes worries too much, but he never lets that stop him from having a great time with his friends. Kai-Lan and her friends can always rely on him for good ideas. Tolee also has a stuffed panda he affectionately named Pandy, and Tolee loves Pandy so much that he cannot imagine being without him. He is the vocalist in Kai-Lan's music group and if he plays a musical instrument, he'll play guitar.
• Hoho (voiced by Angie Wu) is an energetic 3-year-old white monkey and is the smallest and youngest of Kai-Lan's friends which makes him go first in activities. He is very hyperactive and bounces a lot, and whenever he does it, a spring sound can be heard, so he can often be found jumping on his friends' heads. He's full of boundless energy and nothing makes him happier than being the center of attention and sometimes because he's so young, he isn't a good listener that much. Hoho likes bananas, monkeys and stars and he plays them as the resident DJ in Kai-Lan's music group. He can't always control his emotions and can sometimes have a fiery temper when he doesn't get his way, so he sometimes needs help with them. He is very cute, adorable, bouncy, and loves playing.
• Lulu (voiced by Beverly Duan) is a sweet and intelligent 5-year-old light pink rhinoceros. She has a red balloon tied around her horn that helps her fly. Lulu is always seen as being there to help her friends. Her musical instrument is piano or a keyboard. Her favorite fruit is lychee. She likes balloons, tea parties, dancing, playing house and dressing up like a fairy and more. She is very nice, energetic, and sweet.
• At the start of almost every episode, Kai-Lan wakes up Mr. Sun with a tickle so she can start her day. After that, he sometimes bursts out sun fuzzies which are miniature versions of him and they tickle Kai-Lan. At night, he's called Mr. Moon and has moon fuzzies. He plays a French horn like at the beginning of "Tolee's Rhyme Time" as Kai-Lan plays her tambourine and some ladybugs play a pipa.
• In one corner of Kai-Lan's backyard is a teeming mini-metropolis of ants called Ant City who deliver mail and build things. San San is their leader along with his two right-hand ants, Bubu and Fufu. San San is voiced by Zachary Gordon, Bubu by Luke Manriquez, and Fufu by Kyla Rae Kowalewski.

• Howard (voiced by Khamani Griffin) is an owl who first appears in "Ni Hao, Mr. Dragon". He delivers letters and only speaks in hoots.
• Mr. Fluffy (voiced by Elan Garfias) is a hamster and baker who first appears in "Everybody's Hat Parade".
• Mei Mei (Chinese for "younger sister", voiced by Laura Marano) is a shy blue polar bear and is often Mr. Fluffy's assistant and partner.
• Stompy (voiced by Hsiang Lo) is a big, playful blue elephant who made his first appearance in "Safari Pals".
• Gu Nai Nai (voiced by Ming-Na Wen) is Kai-Lan's grandaunt and Ye-Ye's sister. She appears in "Kai-Lan's Trip to China".
• Xiao Xi Gua (meaning "little watermelon") is a baby panda bear. He appears in "Kai-Lan's Trip to China".
• The Peeking Mice are little black mice who are often seen playing music. They are voiced by assorted members of the cast.
• Mr. Hoppy is a frog who starts out as light green with white eye with black pupils within and speaks in ribbits. Then later on, he's dark green with black eyes and talks.
• The Snails (voiced by assorted members of the cast especially Olivia Fine, Kwesi Boakye, Zachary Gordon and Brittany Chen) are found in one corner of Kai-Lan's backyard just like the ants.
• The Worms (voiced by assorted members of the cast especially Olivia Fine, Kwesi Boakye, Zachary Gordon and Brittany Chen) are found in one corner of Kai-Lan's backyard just like the ants.
• The Monkey King (voiced by Jack Cygan) is a monkey superhero who lives in the sky.
• The Fox King (voiced by James Siang'a) is a fox in The Fox Kingdom.
• Xin Xin (voiced by Terrell Ransom Jr.) is a baby fox in The Fox Kingdom.
• The Foxes are red foxes that live in The Fox Kingdom.
• The Bear Queen (voiced by Lucy Liu) is a bear in The Bear Kingdom.
• Tian Tian (voiced by Olivia Fine) is a baby bear in The Bear Kingdom.
• The Bears are brown bears that live in The Bear Kingdom.

The success of Ni Hao, Kai-Lan spawned its own video game series, supported by various gaming consoles and platforms:

• Ni Hao, Kai-Lan: Super Game Day (Wii, PS2) – released, October 26, 2009[14]
• Ni Hao, Kai-Lan: New Year's Celebration (DS) – released, November 5, 2009[15]

The show's success also spawned merchandise from 2007-2014. Kai-Lan also made appearances in Nickelodeon Fit, Nickelodeon Dance, Nickelodeon Dance 2, Dora and Kai-Lan's Pet Shelter, and Team Umizoomi & Dora's Fantastic Flight.