Building on previous environmental flow discussions and a growing recognition that geomorphic and ecological processes are inherent to river functionality and biodiversity, we propose a functional flows approach to managing rivers in contemporary modified riverscapes. The approach focuses on retaining specific functional flows or process-based components of the hydrograph in managed systems, including: peak magnitude flows, recession (seasonal transition) flows, dry season low flows, wet season initiation flows, and interannual variability based on climate. Using a series of case studies and specific examples, we illustrate the importance of each key functional flow. In order to maximize the functionality of these flows and thereby maximize aquatic diversity, restoration of channel-floodplain connectivity and sediment transport processes must be enhanced in both space and time. We further provide considerations for managers that include five guiding principles for developing a functional flows approach or incorporating functional flows into existing environmental flow frameworks. We suggest this approach allows for the development of flow regimes that encompass ecosystem processes alongside varied human needs and can be applied in an adaptive management framework allowing for adjustment in non-stationary river environments.