Summary: Global biodiversity loss is not only driving species extinctions but also eroding the interactions through which animals regulate ecosystem processes. My research in animal ecology shows that this loss of interactions fundamentally disrupts ecosystem functioning, with cascading effects on carbon storage, nutrient cycling, and zoonotic disease dynamics. By integrating field experiments, large-scale datasets, molecular tools, and predictive modelling, I demonstrate that animal-mediated processes—such as seed dispersal, trophic interactions, and host–vector–pathogen networks—are critical yet often overlooked drivers of ecosystem resilience. Furthermore, my work reveals that restoring animal communities can actively enhance ecosystem recovery and climate mitigation potential. Together, these findings advance a new conceptual framework that positions animals as central regulators of ecosystem services, providing a scientific basis for conservation, restoration, and policy strategies in a rapidly changing world.