Techniques for scheduling and executing functions across a plurality of different Functions-as-a-Service (FaaS) infrastructures are provided. In one set of embodiments, a computer system can determine that a function has been invoked, where the computer system implements a spanning FaaS service platform that is communicatively coupled with the plurality of different FaaS infrastructures. In response, the computer system can retrieve metadata associated with the function, where the metadata includes criteria or policies indicating how the function should be scheduled for execution, and can retrieve information associated with each of the plurality of different FaaS infrastructures, where the information includes capabilities or characteristics of each FaaS infrastructure. The computer system can then select a FaaS infrastructure in the plurality of different FaaS infrastructures based on the retrieved metadata and the retrieved information and can schedule the function for execution on the selected FaaS infrastructure.