Habitat loss threatens biodiversity, yet its interaction with behavioural traits remains poorly understood. Using a resource-consumer-predator model in which predators can hunt cooperatively, we show that habitat loss and cooperation interact synergistically to accelerate trophic downgrading. Greater cooperation in hunting increases predator sensitivity to habitat loss, leading to earlier extinction, reduced coexistence, including the vanishment of chaotic coexistence between the three trophic levels. A generalized linear model confirms the non-additive nature of this interaction. Our results highlight the vulnerability of cooperative predators and the need for conservation strategies that account for nonlinear interactions between abiotic stressors and complex biological traits such as cooperative behaviours.