A method and system for garbage collection in a virtualization environment. The virtualization environment includes a virtual machine hypervisor, at least one guest operating system, and at least one application program that runs on each guest operating system. The application program performs memory management using a garbage collection mechanism. The method includes, in response to an operating environment of the application program initiating garbage collection, the garbage collector requesting the guest operating system to assign a memory space and in response, the guest operating system assigns the memory space to the garbage collector. Then garbage collector marks live objects in an original memory space of the application program, and replicates the marked live objects to the assigned memory space. Finally, the garbage collector releases the original memory space of the application program to the guest operating system.