Providing flexible management of heterogeneous memory systems using spatial Quality of Service (QoS) tagging in processor-based systems is disclosed. In one aspect, a heterogeneous memory system of a processor-based system includes a first memory and a second memory. The heterogeneous memory system is divided into a plurality of memory regions, each associated with a QoS identifier (QoSID), which may be set and updated by software. A memory controller of the heterogeneous memory system provides a QoS policy table, which operates to associate each QoSID with a QoS policy state, and which also may be software-configurable. Upon receiving a memory access request including a memory address of a memory region, the memory controller identifies a software-configurable QoSID associated with the memory address, and associates the QoSID with a QoS policy state using the QoS policy table. The memory controller then applies the QoS policy state to perform the memory access operation.