Cross-hypervisor virtual machine conversion. A set of disk images that define a source virtual machine (VM) in a source host computing environment is determined. For each respective disk image, a corresponding overlay image that references the respective disk image is generated. The overlay image that corresponds to a boot disk image is altered to enable a target VM process to be booted from the overlay image on a target host computing device that utilizes a second type of hypervisor. A target VM process that boots from the overlay image that corresponds to the boot disk image is initiated, and the target VM process is configured to access the set of disk images indirectly via the corresponding overlay images.