Embodiments of this application provide a key-value storage method, apparatus, and system, to resolve at least a problem that currently no related solution can combine key-value storage with such efficient storage protocol as an NVMe protocol. The method includes: writing, by a host after detecting a key-value storage request, a first instruction code and address information that are carried in the key-value storage request to a field defined in a protocol, to constitute a first storage request instruction sequence, where the first instruction code is an instruction code defined based on a reserved extension field in the protocol; and interacting, by the host, with the storage controller, so that the storage controller obtains the first storage request instruction sequence. This application is applicable to the field of storage technologies.