The present invention extends to methods, systems, and computer program products for memory pinning through buffer encapsulation. Within a managed execution environment, a wrapper object encapsulates a memory buffer that is to be shared with a native routine executing in a native execution environment. The wrapper object manages operation of a memory manager on a memory heap corresponding to the memory buffer. The wrapper object includes a first function which sets a pin on the memory buffer and returns a pointer identifying the memory buffer. Setting the pin causes the memory manager to cease moving the memory buffer within the memory heap. The wrapper object also includes a second function which releases the pin on the memory buffer.