Centarumon protected a set of ruins on File Island. After Devimon split the island apart, Izzy and Tentomon landed on the piece of island with the ruins on it. Mimi and Palmon arrived at the ruins after finding out that Izzy had landed there. However, Mimi believed that Izzy was ignoring her because he was caught up in translating some heiroglyphics and ran deeper inside the ruins with Tentomon. Izzy started to guide her out, only to realize that what he thought was a glitch was actually Centarumon. Centarumon attacked Mimi and Tentomon, the latter being restricted becuase he needed Izzy to Digivolve. However, after Mimi wound up in a dead end and was about to get hit by Centarumon's Solar Ray, Izzy broke through the wall, revealing that the room was actually right next to the edge of the ruins. Palmon and Tentomon digivolved into Togemon and Kabuterimon, only to be restricted by their own size. However, Centarumon blasted the group outside with his Solar Ray and a combined Electro Shocker and Needle Spray from the two Digimon knocked the Black Gear out of him.
After being freed from Devimon's control, Centarumon revealed that the ruins were actually a temple to the DigiDestined and that the Digivice was the DigiDestined's symbol. He attempted to protect Mimi, Izzy and their digimon from the controlled Leomon, manging to knock his opponent into a wall. However, Leomon easily turned the tables by slamming Centarumon into another wall before turning towards the DigiDestined. The combined light from the two Digivices managed to force Leomon to retreat.
Centarumon was a digimon focused on doing his duty, which was protecting the temple and by extension, the DigiDestined themselves as shown when he fights Leomon. He seems to know Tentomon, as shown by several remarks he makes while chasing Mimi and Tentomon through the ruins.