A method and associated systems for on-demand Internet of Things bandwidth allocation in response to changing sensor populations. An IOT sensor device adds itself to or deletes itself from a cluster of IOT sensors. A physical IOT controller that manages the cluster detects this change, identifies a resulting change in the cluster's bandwidth requirements, and stores this information in a local database. When such a sensor-population change satisfies a triggering condition, the controller requests that a cloud-based application server adjust the controller's bandwidth allocation. The server aggregates this and similar requests from all connected controllers in a global database, and when controller bandwidth requirements satisfy a second triggering condition, the server, using a standard API, asks the cloud-management platform to reprovision the server's virtual bandwidth allocation. The server then distributes the adjusted bandwidth among its IOT controllers, which in turn allocate their adjusted bandwidths among their sensor devices.