Stevonnie is tall and curvy with thick and long arms and legs and a small waist. Their skin is deep tan and they are two black eyes with thick eyebrows, a small nose, and undefined lips. They also have very dark plum hair that is depending on their regeneration is either long and flowy or medium length and poofy. Their gemstone is located on their navel and is pink.
Stevonnie's personality is unique. As a fusion, they do not have a single, distinct personality, but instead have a blend of both Connie and Steven's minds, and they frequently alternate in their control of Stevonnie's behavior and thoughts. They carry the free spirit, friendliness, and fun-loving attitude of Steven and the courtesy, awkwardness, and intelligence of Connie.
When under pressure, Connie and Steven's personalities may become more distinct, as when Stevonnie unintentionally became the center of attention at the rave party they became nervous and had a panic attack, something that can be traced back to Connie rather than Steven.
Stevonnie, like all fusions, possesses an extreme amount super-human strength and agility. Despite being more human than gem, Stevonnie is much stronger than Steven by himself, most likely stemming from Connie's strength and athleticism combined with Steven's superhuman abilities. Stevonnie is strong enough to fight equally with a powerful Quartz Warrior. They appear to be able to utilize all standard Gem abilities, including weapon summoning.
Shield Proficiency: Due to possessing Rose Quartz/Steven's gemstone, Stevonnie can summon Rose's shield. With their enhanced strength as a fusion, they are able to withstand a direct strike from Jasper's crash helmet and absorb the potential knock-back. Like Steven, Stevonnie can also use the shield offensively by throwing it.
Swordsmanship: Stevonnie is skilled in the art of sword-fighting, an ability passed on from Connie.
Sword and Shield: Like Connie, Stevonnie is shown to wield Rose's Sword proficiently when used in conjunction with their shield for fighting both offensively and defensively.
Driving: In "Beach City Drift", Stevonnie drove Greg's new car, the Dondai Supremo.
Superhuman Strength/Agility: Stevonnie is shown to be graceful and agile, as shown when they are running and when they are dancing, which requires nimbleness and agility. They are also shown to be extremely strong, enough to knock the much larger Jasper back a considerable distance and drive her through the monster she was riding with enough force to poof the latter with one slash. In "Know Your Fusion", it is implied by the "Ring the Bell" machine that Sardonyx used to test Smoky Quartz's strength, that Stevonnie's strength is rated (presumably by Sardonyx) as being greater than Pearl's but lower than Garnet's.
Speed of Descent Regulation: While fighting Jasper, Stevonnie remains in the air long enough to throw their shield at Jasper and prepare themself to use Rose's sword. They are shown to gain better control over this ability during their fusion training in "Mindful Education".
Flutter Kick: Stevonnie can lower themself down slowly by moving their legs rapidly forward and backwards.