Mama Mary White is a white bobtail cat, mother to Hello Kitty (Kitty White) and Mimmy White, and wife to George "Papa" White. The family lives in the suburbs of London. She consistently appears wearing a yellow bonnet with a red bow, an apron over a floor-length dress, and shoes. Her size matches her husband's and is roughly double that of her daughters. While typically depicted without a visible mouth across most media, occasional portrayals include one.

Kind, caring, and cheerful, Mary White demonstrates worry and sadness when concerned about her husband or daughters, often becoming quiet during such times. Her domestic roles prominently feature sewing, cooking, and running a successful mending business where neighbors and friends commission clothing repairs. She is the source of Hello Kitty's baking talents. Roses are her preferred flower, sometimes received as gifts from Hello Kitty.

In formal settings, she pairs her signature bonnet and shoes with a dark brown cardigan and beige dress. Her reasonable and nurturing nature is evident when mediating conflicts, such as addressing Mimmy's distress after a baking mishap involving Hello Kitty and a spoiled pie consumed by their friend Robert in "The Wonderful Sisters" episode.

A foundational family figure in the Hello Kitty universe, some narratives credit her as the originator of Hello Kitty’s iconic red bow. Her role extends across various media, including OVAs like "Hello Kitty and Friends" (1989–1998) and later educational series such as "Hello Kitty & Friends: Let’s Learn Together" (2017), where she functions as a supportive home presence while Hello Kitty teaches neighborhood children. Her core attributes—maternal dedication, domestic skills, and emotional stability—remain consistent throughout her appearances, reinforcing her as a stabilizing family influence. Her birthday is documented as September 14th, corresponding to the Virgo zodiac sign.