Blissey has a large, ovoid body with a pink upper body and white lower body. It has hair-like curls on either side of its head. White, wing-like tufts grow from its hips and shoulders, creating the impression of a dress. Its stubby arms and feet are pink and lack any digits. A small, pink pouch on its belly holds a single egg, which brings feelings of happiness and makes a person pleasant and caring if ingested. Blissey can use its fluffy fur to sense sadness, and will rush to anyone feeling sad or ill and attempt to nurse him or her back to health. Its evolutionary line is the only one capable of learning Soft-Boiled. Blissey is a female-only species with no male counterpart. An urban Pokémon, it is rarely seen in the wild.
Blissey appears to be based on a nurse, specifically sharing some physical similarities with Nurse Joy from the anime in both color and hair. Its tendency to carry eggs in a pouch is much like a monotreme or marsupial, but may also simply be based on a general concept of females and motherhood.