Throughout food webs, different animals support a variety of ecological functions that are linked to the stability, condition and resilience of ecosystems. Different measures of the diversity of a food web should be linked to the delivery of these ecological functions, yet, how diversity relates to ecological functioning in many ecosystems remains unclear. We quantified how the functional diversity of fish in a coastal food web relates to the delivery of multiple ecological functions in a coral reef seascape. We used baited and un-baited remote underwater video stations and a series of functional assays to determine how the functional composition of a food web and the delivery of multiple ecological functions varied across 50 coral reef sites in Moreton Bay, Australia. We demonstrate that higher fish functional diversity correlates with multiple ecological functions on reefs, and is identified on reefs that have greater levels of coral recruitment and cover. As ecological functions are key components that modify the resilience of reef systems, identifying that a community that contains a greater diversity of ecological roles and traits results in greater ecological functioning is crucial for the conservation and management of reefs in the future.