Chibiusa retains the same appearance as she does in the original manga. She has bright pink hair done in cone-shaped odangos that resemble rabbit ears with puffy pigtails, and red eyes.
Chibiusa was born in the 30th century on Earth, where people of the Earth and the Moon coexisted in harmony. She was born as the crown princess and heiress to the throne of Crystal Tokyo. Not possessing any magical abilities, like her mother, she was constantly bullied and ridiculed by the children.
Season Two: Black Moon Clan
Chibiusa first appears in Conclusion and Commencement: Petite Etrangere. She falls from the sky through a time portal and lands on top of Usagi's head, and kisses Mamoru in the process. She introduces herself as "Usagi Tsukino" and asks Usagi why she has the same hairstyle and the same name as her. Realizing that she's found the person she's looking for, Chibiusa pulls out a gun and threatens Usagi to give her the Silver Crystal quickly.
She later uses the mysterious magic of Luna-P to bewitch Usagi's Earth family in accepting her as their relative. She is seen carrying a silver key and another Silver Crystal around her neck.
In Act 16-Abduction, Sailor Mercury, when Sailor Moon attempts to interrogate Chibiusa she runs away, scared. She ends up at a park. At this point it's begun raining so Chibiusa shelters under the slide. She is found by Mamoru later, who brings her back to his apartment. When she wakes up, she shows him Luna P and explains that "Small Lady" is her nickname. When asked about the Time Key, Chibiusa says that she needs the key so she can go home. She then asked Mamoru if Sailor Moon was indeed strong as they said she was.
In the seventeenth episode, she had followed Usagi to the arcade where she easily beat the enemy on the Sailor V video game in seconds. When she saw Usagi's parents together, she recalled how her own mother and father loved one another very much and seemed to have forgotten all about her as well. Hurt and lonely, she had run off to the park where it started to rain. She uses Luna P to manifest an umbrella.
In Act 18-Invasion, Sailor Venus, Chibiusa is playing with her new friend, Momoko Momohara, when Usagi and the others return from the battle. Upon seeing the Black Moon earring Mamoru was holding, Chibiusa became overwhelmingly panicked by its presence. Later on, she had stolen Usagi's Crystal Star brooch and attempted to return home to the future. After the battle between Sailor Venus and Calaveras, she begged that Sailor Moon help her save the thirtieth century as soon as possible.
At the beginning of Act 19-Time Warp, Sailor Pluto, Chibiusa, who has just revealed she's from the thirtieth century, asks Mamoru if she can stay with him for the night. Mamoru takes her and Usagi back to his apartment where Chibiusa falls asleep. The next morning, she uses her Space-Time Key to take Sailor Moon, Sailor Venus and Tuxedo Mask to Crystal Tokyo. They meet Sailor Pluto, who is about to attack them for breaking the first taboo but Chibiusa intervenes, explaining that she brought them with her to save her homeland. She then reveals that she's the future Princess of the Silver Millennium. Sailor Pluto grants the group access to the thirtieth century. When they arrive in Crystal Tokyo, they are immediately attacked by Esmeraude and the Boule Brothers. After defeating them, Chibiusa takes them to the Crystal Palace, where they encounter Diana and her own father, King Endymion.
In Act 20 - Crystal Tokyo, King Endymion, Chibiusa is revealed to be the future daughter of Usagi and Mamoru, and is in fact 900 years old, despite her youthful and childlike appearance.
In Act 21 - Complication, Nemesis, Chibiusa feels guilty for Sailor Moon's sudden abduction, as she had stolen the future Silver Crystal to prove to several children that she was really the Queen's daughter and was indeed capable of great strength and power. Due to her taking the Silver Crystal from its rightful place, Crystal Tokyo became defenseless and more vulnerable to the Black Moon's violent attack. Back in the present time, she decides to flee Crystal Tokyo and enter the land Space-Time by herself. While alone, she is approached by Wiseman, who persuades the young princess that he is the only one who can truly understand her. Intrigued and gradually falling under his dark power, she goes with him as a black crescent moon mark appears on her forehead - this is the catalyst to her transformation into Black Lady.
In "Showdown: Death Phantom", upon seeing the nearly lifeless form of Sailor Pluto before her very eyes, Chibiusa finally broke free of the evil energy controlling her and expelled the persona of Black Lady from her mind and body. The Silver Crystal of the future came before her and enveloped her in its pure light of positive energy, transforming her into the standard Sailor form of Sailor Chibi Moon, and she confronts Death Phantom himself for the first time.
In the final episode, she fights alongside Sailor Moon and uses her own Cutie Moon Rod to defeat Death Phantom for good. Afterwards, she gives Usagi the Spiral Heart Moon Rod as a present from her mother, and stays in the twentieth century to train to become an even stronger Sailor Guardian of the Future Moon.
Season Three: Death Busters
Chibiusa stays in the twentieth century timeline to train under Sailor Moon and the Inner Sailor Guardians. By calling out Moon Prism Power! Make Up, she is able to transform by using her own mystical brooch: the Prism Heart Compact. Chibiusa attacks her enemies using the Pink Moon Stick. She introduced herself as one of the defenders of justice to her new friend Hotaru and promised to see her again.
She later came with Tuxedo Mask to see the four Inner Sailors and the three Outer Guardians fight one another, as they were being controlled by Cyprine. She pleaded with them to stop but noticed that Sailor Moon needed her; she joined hands with Sailor Moon and Tuxedo Mask, calling upon on the Holy Grail. She was astonished to see the great powers of the Grail flow into Sailor Moon and enable her to transform into an even greater evolution - Super Sailor Moon. She watched as Super Sailor Moon used her much stronger abilities to turn the others back to normal with Rainbow Moon Heartache. She then listened as Sailor Uranus, Sailor Neptune and Sailor Pluto began to reveal the truth: when their mystical talismans had resonated back when the first Silver Millennium era was annihilated by the evil Queen Metaria. It was then that they had activated to call upon the last of the Sailor Soldiers: the strongest and most feared of all, the Guardian of Doom, Sailor Saturn. She was even more shocked when they said that the Guardian of Death and Destruction was now reborn and reincarnated in none other than her dear friend Hotaru. Refusing to believe that Hotaru was truly evil, she ran to her house, but had ended up awakening the evil female entity that had been gradually awakening deep within, Mistress 9. Unable to defend herself, her regular transformation was reversed as the Prism Heart Compact was grabbed from her chest, mortally wounding her. She was rescued by Super Sailor Moon and Tuxedo Mask, who held her cold and motionlessness form in his arms; noticing that she was not breathing.
Chibiusa was taken to the hospital as the doctors sadly informed a worried Usagi that she close to death. Mamoru then took her lifeless form to his apartment, where he linked his own vital life energy with hers to keep her body alive. As time passed, she gradually began to grow slightly warmer as her spirit was being defended by Hotaru's consciousness. She was fully revived when her spirit and Silver Crystal were returned to her with Hotaru's help. She ran towards her dearest friend, not wanting her to fade away. As tears ran down her cheeks, she agreed that meeting Hotaru was destiny and that she would never ever forget her. She fell to her knees, wondering why her closest friend had to suffer such a sad fate. She pulled herself together and transformed into Sailor Chibi Moon.
- In the opening theme of Season Three, she is shown nude alongside her best friend Hotaru.
- She is the main focus for the second ending theme for Season 3.