Noelle is a 15-year-old girl with a slender build and pink eyes. She possesses long, silver-colored hair, which is usually tied in pigtails, with her center bangs over her forehead. Additionally, she wears a pair of purple stud earrings with a cross flory fitchy shape and a silver bracelet on her left wrist.
She wears a sleeveless, backless, short purple dress covered by a silver-colored blazer. The blazer has a backless design with sleeves attached at the back that extend slightly beyond her elbows with gold-colored cuffs. The blazer also has a pair of House Silva pins attached to it around her collarbone area. Additionally, it has frilly edges and a rounded tailcoat that extends down to her knees. Furthermore, the blazer extends up to her neck where it has frilly edges and is held together by a gold locket. She wears a brown leather belt that supports her pouch, which has a similar color and gold ornaments at its corners. The pouch hands on her right side, and contains her grimoire. She also wears a pair of silver-colored leg warmers with a gold-colored cuff at both ends and a pair of sandals.
Having been born into the royal family, Noelle can seem arrogant and vain. This can be seen when she denies Asta's act of friendship while proclaiming that she has not given him permission to talk to her.
This also causes her to have difficulty admitting her failures, as she often tries to find excuses or blames her mistakes on somebody else. After finally coming out of her difficulties in admitting her mistakes, Noelle can also be seen as very reserved in expressing her delight over her achievements where she would rather suppress those feelings and shows her usual stern expression. She has a supposedly high sense of taste for items, as can be seen when she says that Magna Swim's broom is lame.
However, due to having been rejected by her own family who had noticed her lack of control over her Magic Power, Noelle developed a slight inferiority complex to her more accomplished brothers and sister. This inferiority complex leads Noelle to try and prove them wrong to the point where she will overexert herself during training. Additionally, she is skeptical of the people around her since she expects them to react the same way that her family did. She is also rather modest, as she is mortified when she realizes her shirt is torn, showing her breasts slightly after the dungeon mission, and is also slightly embarrassed wearing her bikini at the beach.