Perfect. A spontaneous fusion of love, as impossible as it was inevitable. Even I could not have guessed it. Steven is capable of fusing with human beings. I could not be prouder of Steven and Connie.
|—Garnet, Guide to the Crystal Gems|
Stevonnie is currently the shortest fusion in the series. They are taller than Amethyst and Pearl, but are a few inches shorter than Garnet. They have an average/athletic build consisting of Connie's slim figure with Steven's chubby, stocky features, curly black hair that reaches to their thighs, and a complexion slightly darker than Steven's. Their attire consists of a cyan tank top over a reddish-pink t-shirt with a gold-yellow star on it, Steven's jeans as cutoff shorts, and bare feet. It should be noted that their clothes appear with minor variations throughout Stevonnie's formations. Stevonnie appears to be a teenager, similar in height to the other teenage characters (Lars, Sour Cream, etc.), if not a few inches taller. Stevonnie is considered to be very physically attractive, as the citizens of Beach City seem to be in awe of their appearance and personality from meeting them.
I wish you were here. If we were together, it would be okay. But we are together, and it's not. I'm alone...
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, appears to possess some degree of both super-human strength and agility. This is evidenced by the fact that their dance moves during the rave would require a level of physical capability and nimbleness above that of the average human and more similar to that of a Gem.
This is most likely a result of Steven, being a half-Gem, inheriting a fraction of his mother's supernatural physical capabilities. He is occasionally shown to be capable of feats of strength which would be impossible for a human boy of his age, such as forcing the possessed breakfast monster into the pool of lava in "Together Breakfast", tearing an arcade machine apart with his bare hands in "Arcade Mania", lifting Jenny in "Joy Ride", and punching the dashboard in Greg's van hard enough to dent it and activate the air bag in "The Return". However, it is unknown if Stevonnie inherited standard Gem abilities, such as poofing and bubbling, from Steven.
If Stevonnie's able to summon a weapon, it would probably be the Rose Quartz shield. Because they're a fusion of Connie as well as Steven, it's safe to assume Stevonnie has inherited some of her abilities, such as her wide intellect and her sword-fighting skills. This is also because Connie is not a Gem, and does not contribute a summoned weapon to the fusion.
- "Alone Together" (debut)
- "We Need to Talk" (cameo)
- "We are the Crystal Gems" (cameo)
- "Fusion (short)" (screen)
- It has been confirmed that Stevonnie will reappear in a future episode. 
- Stevonnie is the first human-Gem fusion.
- The original Stevonnie concept sketches included another outfit design: a combination of Connie's dress on the left and Steven's T-shirt and jeans on the right, connected by zig-zagging lines and Steven's usual sandals.
- According to Rebecca Sugar, Stevonnie is a "...metaphor for all the terrifying firsts in a first relationship, and what it feels like to hit puberty and suddenly find yourself with the body of an adult, how quickly that happens, how it feels to have a new power over people, or to suddenly find yourself objectified, all for seemingly no reason since you’re still just you..." 
- Stevonnie's portrayed age may have been created by combining Connie's and Steven's respective ages.
- Stevonnie's gemstone is the same as Steven's (and Rose Quartz's).
- Stevonnie's gender has not been specified, although it has been confirmed that they use gender-neutral they/them pronouns. 
- Stevonnie is the first character and only fusion to use they/them pronouns.
- Stevonnie's voice actress had to be instructed by Zach Callison to replicate Steven's laugh.
- The name Stevonnie came from Amethyst, who named them by mashing their names together. It is unknown if Stevonnie will be re-named in the following events or if they have an alias.
- In "Guide to the Crystal Gems", Garnet describes Stevonnie as 'perfect' due to Steven and Connie's ability to form a stable fusion without training or even trying, and admits even she couldn't foresee this.
|Stevonnie's gem is placed where the navel would be, as with Steven and Rose Quartz. It has a pentagonal facet.|