Concepts and technologies disclosed herein are directed to an auto-scaling software-defined monitoring (“SDM”) platform for software-defined networking (“SDN”) service assurance. According to one aspect of the concepts and technologies disclosed herein, an SDM controller can monitor event data associated with a network event that occurred within a virtualized IP SDN network that is monitored by a virtualized SDM resources platform. The SDM controller can measure, based upon the event data, a quality of service (“QoS”) performance metric associated with the virtualized SDM resource platform. The SDN controller can determine, based upon the QoS performance metric, whether an auto-scaling operation is to be performed. The auto-scaling operation can include reconfiguring the virtualized SDM resources platform by adding virtual machine capacity for supporting event management tasks either by instantiating a new virtual machine or by migrating an existing virtual machine to a new hardware host.