Conservation actions, like protected areas, have been implemented widely to arrest biodiversity declines, but these structural tools are rarely informed by empirical data on the functional characteristics of food-webs, ecological functioning, and resilience. Functional redundancy and complementarity are pivotal characteristics of ecosystems that link biodiversity to ecosystem functioning. High redundancy can help to maintain the delivery of an ecological function through time when significant species are removed or lost. By contrast, high complementarity within food-webs can help to support a diversity of functions, further promoting the resilience of ecosystems to disturbances. Here we highlight four concepts to support tighter integration of functional complementarity into conservation. Firstly, it is crucial that management decisions and actions are informed by data on the rates and distributions of key ecological functions that are demonstrably linked to the maintenance of ecosystem structure and resilience. It is then important to develop and integrate appropriate metrics (e.g. functional diversity metrics) of community change that incorporate the functional composition of food-webs and key ecological functions. Managers should then identify species (e.g. dominant generalists or pests) that could limit the positive outcomes of conservation, and finally monitor, adapt, and set realistic goals for management that focus on diverse functioning.