How can I assign the Task to a User if a Specific value is selected from a Custom Field?

[Wajahath Farooq]

How can I assign the Task to a User if a Specific value is selected from a Custom Field?

Please let me know How can I achieve this scenario.

[John Funk]

HI Wajahath - Welcome to the Atlassian Community!

You can do that with an Automation for Jira rule. 

Create a rule with a Field Value Changed trigger. Then select the custom field. 

Then add a Condition for Issue Fields Condition and put in the value for the custom field. 

Then add a new action for Edit Issue. Select the Assignee field and add the user.