Providing fine-grained Quality of Service (QoS) control using interpolation for partitioned resources in processor-based systems is disclosed. In this regard, in one aspect, a processor-based system provides a partitioned resource (such as a system cache or memory access bandwidth to a shared system memory) that is subdivided into a plurality of partitions, and that is configured to service a plurality of resource clients. A resource allocation agent of the processor-based system provides a plurality of allocation indicators corresponding to each combination of resource client and partition, and indicating an allocation of each partition for each resource client. The resource allocation agent allocates the partitioned resource among the resource clients based on an interpolation of the plurality of allocation indicators. Because each allocation indicator may be different for each combination of resource client and partition, interpolation of the allocation indicators provides a higher-resolution aggregate resource allocation for each resource client.