3B3 functioned as a B1 battle droid within the ranks of the Trade Federation Droid Army. During the Naboo invasion that occurred on the planet of Naboo in 32 BBY, 3B3 stumbled upon Jedi Knights Qui-Gon Jinn and Obi-Wan Kenobi, as well as the Gungan Jar Jar Binks, as they were covertly entering the capital city of Theed. 3B3 issued an order for them to relinquish their weaponry, but Jinn swiftly neutralized the droid.
As a B1-series battle droid, 3B3 was a soldier in the Droid Army of the Trade Federation during the invasion of the planet Naboo in 32 BBY. 3B3 was involved in the seizure of Theed, the capital city of Naboo. During this conflict, 3B3 crossed paths with Jedi Knights Qui-Gon Jinn and Obi-Wan Kenobi, who had traveled to Theed via the Solleu River in order to rescue Padmé Amidala, the queen of Naboo. They were also in the process of extracting their Gungan companion, Jar Jar Binks, using an ascension gun cable attached to their tribubble bongo.
3B3 commanded the Jedi to halt, leveling a blaster pistol at them. Jinn responded by turning and promptly, yet casually, severing the droid's head with his lightsaber. Simultaneously, 3B3 discharged its blaster, striking the grappling hook cable and causing the bongo to plummet over a waterfall. Kenobi observed the droid's remains as they fell to the ground.
3B3's designation was a truncated form of its unique identification number, typically assigned by Trade Federation technicians. Like all B1 battle droids, 3B3 possessed a height of 1.91 meters, was programmed with masculine traits, and featured tan armor plating.
George Lucas conceived 3B3 for the prequel trilogy film Star Wars: Episode I The Phantom Menace. Although 3B3 was present in early drafts of the screenplay, the character was ultimately omitted from the final version of the film, which debuted on May 19, 1999. However, prior to the film's release, 3B3 made an appearance in its Illustrated Screenplay, which was published on April 21, 1999.
The encounter between 3B3 and the Jedi is depicted with slight variations across different adaptations of The Phantom Menace. The picture book titled Dangers of the Core holds the distinction of being the first source to provide a visual representation of 3B3. Penned by Jim Thomas, illustrated by Boris Vallejo, and released on May 3, 1999, the book portrays 3B3 arriving and standing in the Solleu River just as Kenobi is pulling Jinn ashore. Following Binks' arrival, 3B3 directs a blaster at him before being bisected by Jinn. In the Mighty Chronicles adaptation, authored by John Whitman and also published on May 3, 1999, 3B3 encounters the Jedi on a riverbank situated just outside Theed, rather than within the city itself. In Episode I: Obi-Wan Kenobi, a one-shot comic written by Henry Gilroy and illustrated by Martin Egeland, and published on June 2, 1999, the droid instructs the Jedi to "hold it" instead of demanding that they drop their weapons, as depicted in other sources.
The deleted scene, featuring Jinn, Kenobi, and Binks emerging from the Solleu River, was incorporated into the DVD release of The Phantom Menace on October 16, 2001, although 3B3 was not present in this particular sequence.