The Butterfly Miraculous, also called the Moth Miraculous, is a brooch that, whenever Nooroo inhabits it, transforms the wearer into a butterfly-themed superhero with the power of transmission. The brooch is currently owned by Gabriel Agreste, who uses it to transform into Hawk Moth for evil purposes — specifically, creating supervillains who attempt to steal Ladybug's and Cat Noir's Miraculouses.
When not transformed, the brooch is oval-shaped and its front is purple. It opens up like a locket, in which an image can be placed. The edges of the brooch and the back of the front part are gray metal, some of it branching out on the outer area of the front of the brooch. When Nooroo inhabits the Miraculous, it becomes a dark purple button, with four light pink strands of fabric coming out from it, making it resemble a butterfly or moth.
Even when disguised, the Butterfly Miraculous grants its wielder the ability to sense positive or negative emotions in order to precisely pinpoint a targeted person's identity. Able to sense various people and their emotions, the wielder usually targets a person with the strongest emotions for the best manipulation. While able to sense emotions, the holder cannot read minds.
Akumatization is the Butterfly Miraculous's superpower. The wielder can energize a butterfly, which turns it black and into an akuma, to be sent to possess an object of the person. Then, the Butterfly Miraculous holder is able to communicate with the person to offer him or her powers. Once they accept, they transform into a super being. In addition, the wielder can telepathically connect to the akumatized person to talk with them and perceive what that person perceives. If the akumatized person is using their powers wrongly or not the way the holder wants them to, the holder can cause pain to the akumatized person by controlling the person's body to a certain extent, or take away their powers. In "The Collector", it is revealed that Butterfly Miraculous holders can akumatize themselves; to do so, however, they need to first create an akuma and then give up the possession of their Miraculous.
These powers, however, do have their limitations. Hawk Moth is only able to make one akumatized villain at a time, and in order to akumatize another victim, he has to remove the akuma from the initial target first. However in "Catalyst (Heroes' Day - Part 1)", he shows he can manage to get around this weakness by creating a villain whose power is to enhance his own, allowing him to create as many akumas and akumatize as many people as he wants.
It can also give people hope to fight when the world is in danger.
The power to cause pain to an akumatized person or remove their powers is supposed to be a safeguard to prevent the person from using their powers wrongly or evilly.
Although it has yet to be seen, people feeling insufficient emotion can decline to become akumatized, such as those targeted by Hawk Moth if they don't despair enough.
In "Despair Bear" and "Gigantitan", it was shown the akuma would stop if its target has overcome his or hers negative emotions.
In "Catalyst (Heroes' Day - Part 1)", Hawk Moth's powers were increased, and he no longer needed the consent of his target, though the akuma still needed negative emotions to take hold of its target.
The Butterfly Miraculous glows whenever someone is feeling negative emotions.
In "Ladybug & Cat Noir", the inactive Miraculous is large enough to sit in Gabriel's palm and contain a photo, but in "The Collector", the inactive Miraculous is notably smaller, being the same size as the active one is without wings.
As shown in "Simon Says", akumas and akumatized villains can retain their powers even when the Miraculous holder is not transformed.
The Butterfly Miraculous's user is seemingly immune to the effects of the Akumatized villains, as he was not trapped in one of the Bubbler's bubbles despite being an adult, nor was he turned into a knight from Darkblade's barrier.
However, this does not apply when the Miraculous is inactive, as shown in "Simon Says", nor to non magical powers as shown in "Robostus".
However, in "Catalyst (Heroes' Day - Part 1)", not only was Hawk Moth affected by the titular villain, he counted on it to fulfil his plan.