Biodiversity loss and its effects on humanity is of major global concern. While a growing body of literature confirms positive relationships between biodiversity and multiple ecological functions, the links between biodiversity, ecological functions and multiple ecosystem services is yet unclear. Studies of biodiversity–functionality relationships are mainly based on computer simulations or controlled field experiments using only few species. Here, we use a trait‐based approach to integrate plant functions into an ecosystem service assessment to address impacts of restoration on species‐rich grasslands over time. We found trade‐offs among functions and services when analysing contributions from individual species. At the community level, these trade‐offs disappeared for almost all services with time since restoration as an effect of increased species diversity and more evenly distributed species. Restoration to enhance biodiversity also in species‐rich communities is therefore essential to secure higher functional redundancy towards disturbances and sustainable provision of multiple ecosystem services over time. Positive relationships found between biodiversity and multiple ecological functions leading to multiple ecosystem services are mainly based on computer simulations or controlled field experiments using only few species. We use a trait‐based approach to integrate plant functions into an ecosystem service assessment to address impacts of restoration on species‐rich grasslands over time. We show that the existence of trade‐offs among services at the individual species level could be mitigated at community level by high species diversity and more evenly distributed species.