Haiden Deegan grew up riding around Metal Mulisha with his dad Brian and was racing 50s at Ponca City with Mulisha support in 2013. Dangerboy then worked through the amateur classes and joined Yamaha's Star Racing program in 2021. He earned Rookie of the Year honors in both Supercross and Pro Motocross during his first full pro season.

He won the 250 SuperMotocross championship in 2023 and defended it in 2024. He added the Pro Motocross 250 championship in 2024, the 250SX West title in 2025 and another outdoor title that summer. His 2025 West title came a round early after four wins and nine podium finishes.