Belldandy serves as a first-class goddess with an unlimited license from Heaven's Goddess Relief Agency. Her character draws inspiration from Norse mythology, specifically the Norn Verðandi, who represents the present. She is one of three sisters: Urd embodies the past and Skuld the future, together forming the fates. The name Belldandy originates from the Japanese transliteration of Verðandi, adapted due to linguistic constraints.

Her primary narrative begins when college student Keiichi Morisato accidentally summons her while attempting to order food. As part of her duties, she grants Keiichi one wish. Skeptical of her identity, he wishes for "a goddess like you to stay by my side forever," forming a binding contract that anchors her to Earth. Though possessing the power to nullify this contract, Belldandy chooses to honor it due to her developing affection for Keiichi. They reside at Tariki Hongan Temple in Nekomi City, later joined by her sisters, leading to supernatural complications.

Belldandy epitomizes kindness, patience, and selflessness. She exhibits unwavering empathy, sensing emotions through auras and striving to alleviate distress, extending forgiveness even to those who harm her. However, her devotion to Keiichi creates vulnerabilities; intense jealousy triggered by other women approaching him causes uncontrolled magical outbursts manifesting as violent "jealousy storms." Misunderstandings suggesting Keiichi might reject her can induce profound insecurity. Her occasional naivety regarding human social nuances stems from an idealistic worldview focused on seeing goodness in others.

As a first-class goddess, Belldandy commands immense magical power, primarily aligned with wind and air. She summons gusts or tornadoes, levitates, teleports via mirrors, heals minor injuries by accelerating metabolism, communicates with animals and machines, and alters clothing appearances. Her singing, renowned as Heaven's finest, can rejuvenate lifeless areas or perform potent spells like the lullaby Rarihozen. To maintain Earth's balance, she wears a sealing earring restricting her full strength. Only once, during the Lord of Terror arc, does she partially remove this seal, revealing that even one ten-millionth of her power can reconstruct entire buildings. Her angel, Holy Bell, amplifies her magic and mirrors her physical or emotional state, such as falling comatose when Belldandy is infected by a virus.

Beyond magic, Belldandy excels in domestic activities and possesses above-average human intelligence, attending college classes with Keiichi. A unique trait is her sensitivity to soda; consuming even small amounts induces intoxication, causing uncharacteristically chaotic behavior, while alcohol has no effect.

Her character evolves across media, confronting personal flaws. In the movie storyline, latent possessiveness of Keiichi is exploited by her mentor Celestine, who manipulates jealousy of earth spirit Morgan Le Fay to advance destruction. This arc highlights her capacity for inner conflict and growth, leading her to recognize love—not duty—as her reason for staying. Early manga chapters depict her as more impulsively expressive, while later adaptations present a calmer, more reserved demeanor. Her relationships deepen as she acknowledges Urd and Skuld as essential supports and learns defensive assertiveness when loved ones are threatened.

Belldandy’s background includes familial revelations, such as her mother, the goddess Ansuz, harboring a rivalry with Urd’s mother, the demon lord Hild. Despite her divine lineage, her role in maintaining Yggdrasil, Heaven's reality-governing system, is minimal compared to Urd's administrative duties or Skuld's debugging expertise. Her focus remains on human-centric welfare through the Goddess Relief Agency.