A kind and clumsy girl, Marinette is cheerful, creative, and generous. She loves fashion, her friends, family, and her crush Adrien being some of her motives to complement herself. Despite her outgoing and empathetic personality, Marinette struggles with self-confidence and self-esteem: In a situation she deems urgent, like doing something for Adrien or losing a something that will expose her secret identity, she becomes very nervous, awkward, and quick to panic. Marinette cares deeply for other people, usually putting their feelings and interests even before her own, in some cases at a personal cost. Despite being genuinely kind, she has her limits, such as in "The Evilistrator" when she gets irritated with Chloé to the point that she refuses to continue watching her in order to protect her as Ladybug.

Marinette can act impulsively and irrationally at times, as shown when she tried to deflect the false accusation of "stealing" Chloe's bracelet onto others who are also innocent. She also expresses jealousy whenever other girls such as Chloé or Lila flirt with Adrien, sometimes causing her to act irrationally, even abusing her powers as Ladybug to keep them away. However, she tends to learn from her mistakes and become a more open-minded, understanding person.