Methods and apparatus for facilitating efficient Quality of Service (QoS) support for software-based packet processing by offloading QoS rate-limiting to NIC hardware. Software-based packet processing is performed on packet flows received at a compute platform, such as a general purpose server, and/or packet flows generated by local applications running on the compute platform. The packet processing includes packet classification that associates packets with packet flows using flow IDs, and identifying a QoS class for the packet and packet flow. NIC Tx queues are dynamically configured or pre-configured to effect rate limiting for forwarding packets enqueued in the NIC Tx queues. New packet flows are detected, and mapping data is created to map flow IDs associated with flows to the NIC Tx queues used to forward the packets associated with the flows.