AZ467818 - Generally Available: Azure Functions supports .NET 9

Azure Functions now supports .NET 9 for applications using the isolated worker model. You can now use the improved performance of .NET 9, write your code with the new language features of C# 13, and more. Support is being enabled for Windows and Linux on the Consumption, Elastic Premium, and App Service plan hosting options. Please note the immediately following the announcement, some options may not yet be available in all regions, and apps may temporarily experience additional cold start when using .NET 9. 

You can start using .NET 9 with Functions projects using the isolated worker model by changing the target framework and updating to the 2.0.0 versions of Microsoft.Azure.Functions.Worker and Microsoft.Azure.Functions.Worker.Sdk.