From your Shopify admin, go to Online Store > Domains.
    Click Connect existing domain:

    Enter the domain you want to connect:

    Click Next.
    Click Connect automatically:

    In the Sign In window, log in to your GoDaddy account:

    Click Connect:

Your GoDaddy domain is now connected to your Shopify store.
Note
If you experience problems setting up your domain automatically, try setting it up manually.

Set up your GoDaddy domain manually

If you're having trouble connecting your domain automatically, then you can connect it manually from the GoDaddy website.
Steps:
    In the My Products > Domains section, click Manage All.

    On the My Domains page, click Use my domain next to the domain you want to connect:

    In the Connect to an existing site section, click Connect:

    In the Online Stores section, click Shopify.
    Click Connect Domain.
    Click Verify connection in your Shopify admin to confirm that your custom domain has been connected to your store.

It can take up to 48 hours for changes to take effect.