An example method of secure attestation of a workload deployed in a virtualized computing system is described. The virtualized computing system includes a host cluster and a virtualization management server, the host cluster having hosts and a virtualization layer executing on hardware platforms of the hosts. The method includes storing, in a trust authority, a pre-defined attestation report for a workload executing in a virtual machine (VM) managed by the virtualization layer, the pre-defined attestation report including a hash of at least a portion of an image of the VM; receiving, at the trust authority from a security module of a host in which the VM executes, an attestation report generated by measuring memory of the VM; comparing the attestation report with the pre-defined attestation report; and generating an indication of validity for the workload based on a result of the comparison.