Providing automated quality-of-service (‘QoS’) for virtual machine migration across a shared data center network, including: identifying, by a virtual machine migration module, a virtual machine to migrate from a source host to a destination host; determining a migration cost for migrating the virtual machine from the source host to the destination host; identifying based on the migration cost a least congested network path between the source host and the destination host and a bandwidth to be used for migration such that migration completes within a user specified time limit; and initiating transmission of the virtual machine from the source host to the destination host over the least congested network path, including reserving bandwidth across the shared data center network for transferring the virtual machine from the source host to the destination host in dependence upon the migration cost.