It appears that the Azure Automation cmdlet Start-AzureAutomationRunbook, in the Azure PowerShell module v0.9.3, has been updated to include a new parameter named RunOn. This parameter can be used to execute a runbook on a Hybrid Worker. The parameter is not yet listed on TechNet, or with the Get-Help command. However, by running Get-Command against the cmdlet you can see the RunOn parameter. The help message for this parameter states, “Optional name of the hybrid agent which should execute the runbook”. When using this parameter you just need to specify a string value with the name of the Hybrid Worker you want the runbook to execute on.
Start-AzureAutomationRunbook -AutomationAccountName "AutoLab" -name "Clear-Logs" -RunOn "LabHybrid"