Agnimon features in the Digimon Frontier theatrical film "Revival of the Ancient Digimon!!" (internationally titled "Island of Lost Digimon"), set during the main series at an unspecified point. In this self-contained story, Agnimon manifests after Takuya Kanbara spirit evolves to intervene in the Wandering Island's civil war between human-type and beast-type Digimon factions.

The character confronts Dinohyumon, leader of the human-type Digimon army, forcibly subduing him by slamming him against a wall to halt hostilities. This occurs when Agnimon and Garummon (Lobomon) simultaneously intervene to separate the warring factions led by Dinohyumon and Gryzmon. During this clash, Agnimon and Garummon execute their unison attack Shining Burn Slash, surrounding the opponent with a flame dragon before bisecting it with holy light.

Later, as artillery fire threatens ruins housing a critical mural, Agnimon's human form Takuya spirit evolves alongside Koji—becoming Vritramon (BurningGreymon) while Koji becomes Wolfmon (Lobomon)—to engage the battling armies and bombarding tanks. This evolution responds to heightened danger against the group reconstructing the mural inside the ruins. Agnimon utilizes established fire-based martial arts and techniques like Pyro Punch (Burning Salamander) and Pyro Tornado (Salamander Break) throughout the conflict, without unique character development or accessing forms beyond those seen in the series.