He appears as a small childlike man in an ill-fitting Batman costume, with a black lightning bolt instead of the Bat-insignia. Bat-Mite possesses near-infinite magical powers and comes from another dimension, much like Mr. Mxyzptlk. In Bat-Mite's dimension, his people idolize the heroes of the DC Universe and impersonate them, acting out their heroic adventures. Bat-Mite's favorite is Batman, and visited Batman on many occasions, often setting up strange events to see his hero in action. However, Bat-Mite is more of a nuisance than a supervillain, and often leaves when he becomes aware that he had angered Batman.

Bat-Mite regularly appeared in Batman, Detective Comics, and World's Finest Comics for five years. Bat-Mite and Mr. Mxyzptlk teamed up four times in the pages of World's Finest Comics to plague Superman and Batman together, as well. However in 1964, when the Batman titles were revamped he vanished. He would later appear teaming-up with Mr. Mxyzptlk and "Bat-Mite's New York Adventure" from Detective Comics #482 where he traveled to the DC Comic offices asking for his own comic. He appeared again in Legends of the Dark Knight, but he was more than likely a hallucination of a drug-addled criminal named Bob Overdog. He also appeared in the One-Shot Mitefall ( a spoof on Knightfall with Overdog in the role of Azrael). In issue 6 of the 1999 World's Finest miniseries, Mr. Mxyzptlk encountered Bat-Mite, shortly after being mistaken for him by Overdog. While in this story the post-Crisis Bat-Mite encountered Batman for the first time; Superman and Batman subsequently concluded that Mxyzptlk had created him, inspired by Overdog's ravings.

In Superman/Batman #25, it was revealed that the Joker had taken Bat-Mite's powers by absorbing his essence and was freed by Bizarro. Since then Bat-Mite has fully re-established into the current continuity. He recently appeared in Batman #672 after Batman was shot in the chest by Sleeper and had a heart attack.