Sofia has shoulder-length wavy auburn hair (sometimes she ties it in a ponytail), light blue eyes and fair skin with rosy cheeks.
She usually wears a princess gown of a lilac bodice trimmed in two lines of pearls down the front and along the neckline and wings on the skirt, a pearl-hemmed and studded lilac petaled skirt with a row of great lace drops and trumpets each arranged like a four-leaf clover or cross on a nimbus, and a yellowish petticoat with a lilac band; a swirly tiara inset with pink sapphires, white pearls, and a turquoise diamond; violet slippers with bows and mid heels; and the royal family's Amulet of Avalor, a huge fire opal drop cabochon on a swirly silver backing topped with three sapphires and on a silver necklace wrapped over amethyst beans. In the pilot for her debutante ball her dress had elaborate lacework on the shoulders and fourteen scrolls and terminal cloverleaves about each nimbus.
During the crossover her amulet has turned pink and her dress turned into a violet gown like when she was a commoner, her Derby outfit, and sorceress robe, where her bodice now has white vines on a pink front between the only lines of pearls each clustered with eight smaller pearls and her sheer overskirt has shafts of four spade-like pairs of tendrils against beams all greater below the next over 15 drops arranged as daisy petals over the violet skirt with three white fan stripes between each shaft. She also wears purple slippers and white stockings. But earlier the Disney websites featured her in an intermediate glittery outfit of the purple skirt with opalescent clover-nimbus motif, pink petticoat, and violet bow-tie slippers, and stockings and a purple amulet, which she did not wear in the crossover, but more often in the episodes since "The Bamboo Kite". So both of her special outfits in the television specials did not become employed regularly instead of the simpler ones. Sofia's promotional art and merchandise broadly depart on the dress and amulet.
When she goes on outings she usually wears a violet equestrian suit for riding, of a cap with bow, jacket, trousers, and boots, but her shirt is lilac like her flying pony Minimus. When she has a Buttercups meeting she wears what essentially looks like a Girl Scouts uniform of the 1960s which, much like the Fireside Girls in Phineas and Ferb, has a beret with emblem, shirt, and skirt here of shades of yellow, but with uniform tan vests of badges, tan shoes, and red socks. Each Buttercup has also worn a green or red backpack. Otherwise when Sofia travels on foot she wears a long dress with three stripes at the bottom, a thick coat, sometimes a bow, and a narrow-brimmed hat with a headstrap and a band with her tiara emblem.
Sofia's amulet lets her change to the size of a rodent or wee sprite or into a mermaid, whenever she needs to. As a mermaid she has a violet tail, lilac top with sheer waist frill, bra of several pink scallop shells and a amethyst-beaded strap, bracelet of starfish and seashells, and golden tiara of stars, a pair of seahorses, and some gems.