Nicole greatly resembles her oldest son, Gumball, who is, like her, a cat. She has light blue fur, and is somewhere between Richard and Gumball in height. Her head is shaped similarly to Gumball's, except Nicole's whiskers are shorter than her son's, and she has visible eyelashes. The inside of her mouth is light pink and her tongue is pink, and her nose is pink.
Her usual outfit consists of a white collared shirt with a button that symbolizes the Rainbow Factory, where she works. She wears a short, light gray skirt to go along with it. Like the rest of her family (excluding Anais and Darwin), she spends most of her time barefoot.
In Season 3, Nicole's eyes are permanently round along with the rest of her family.