Embodiments of this application provide an API hybrid multi-tenant routing method and system, as well as an API gateway. The method includes: after receiving an API request message sent by an API caller, obtaining an APP key carried in the message; obtaining, based on a multi-tenant routing policy table, an API running instance URL list corresponding to the APP key; determining an API running instance URL in the API running instance URL list; and returning the API running instance URL to the API caller. The APP key is used to identify the API caller. The multi-tenant routing policy table stores a mapping relationship between the APP key and the API running instance URL list. The API hybrid multi-tenant routing system is a functional module in the API gateway.