Gabumon is a Reptile Digimon and the partner of Matt Ishida in Digimon Adventure. Physically, Gabumon stands about two and a half feet tall and has yellow skin, a ten-inch horn on its head, and a tail with regularly spaced bumps. Its most distinctive feature is the blue fur pelt it wears on its back, which comes from a young Garurumon. This pelt gives Gabumon a dog-like appearance, with four teeth and three claws attached to each limb, but underneath it is revealed to have a lizard-like muzzle. Gabumon has red eyes, a sky blue belly with symmetric pink motifs, and its hands are usually curled around handles on the inside of the pelt to keep it in place. The pelt is removable, and Gabumon is extremely shy about being seen without it.

In terms of personality, Gabumon has a mellow and rather cool attitude toward life, though at times it can be timid and obedient. It is not one to openly offer help unless those it cares about are harmed. The creature is utterly devoted to its partner, Matt Ishida, and this loyalty is the core of its character. Gabumon follows Matt even when the boy is tricked into fighting against his own friends, demonstrating a significant amount of blind faith. However, this devotion also allows Gabumon to be the one who brings Matt back when he falls too far, eventually convincing him to rejoin the other DigiDestined by promising they would be friends for life. The partnership is complementary, as Matt can be cool and conflicted while Gabumon is more emotional and steadfast.

Gabumon first meets Matt in the Digital World in its In-Training form, Tsunomon. It quickly digivolves to its Rookie form to protect Matt from an attacking Kuwagamon, and this becomes its preferred form. The Rookie level is where Gabumon spends most of its time, as remaining in higher forms requires a great deal of energy. Throughout Digimon Adventure, Gabumon plays a decisive role in many battles. One of the most notable events highlighting its caring nature occurs when Matt is trapped in a cold cave with hypothermia; Gabumon removes its fur pelt to give to Matt, even though doing so makes it vulnerable and causes it to catch a cold. Later in the series, Gabumon can Warp Digivolve to its Mega form, MetalGarurumon. During the battle against the evil Diaboromon in the movie, Gabumon as MetalGarurumon fuses with Agumon as WarGreymon to become the powerful Omnimon.

Gabumon's key relationship is with its partner, Matt Ishida. This bond is the primary driver of its actions. Gabumon also frequently acts as a protector for Matt's younger brother, T.K., and shares a friendly rivalry with Tai's partner, Agumon. In the sequel series Digimon Adventure 02, Gabumon returns to help a new generation of DigiDestined fight against the Digimon Emperor and later assists in battles when Digimon invade the real world.

The character experiences notable development through its unwavering commitment to its partner. When Matt becomes lost in his own conflicts and turns against the group, Gabumon remains by his side, not out of agreement but out of friendship and an understanding that Matt needs to find his own way. This loyalty serves as the anchor that eventually helps Matt rediscover the true meaning of friendship. Over time, Matt and Gabumon reach a point where they can communicate without words, comfortable in the silence of their deep bond.

Gabumon possesses several notable abilities in its Rookie form. Its primary attack is Blue Blaster, also known as Petit Fire, in which it releases a stream of blue flames from its mouth. Its other main attack is Horn Attack, also called Little Horn, where it charges at an opponent using the horn on its head. As it digivolves, Gabumon gains access to increasingly powerful forms, including the wolf-like Champion form Garurumon, the humanoid Ultimate form WereGarurumon, and the heavily armed cyborg Mega form MetalGarurumon.