If your website is hosted on WordPress.com, it can be a bit tricky to verify your Mastodon account. Here are the steps that worked for me:

Configure your rel=”me” for Mastodon on WordPress.com

1. Log in to WordPress.com.
2. Follow these instructions for adding a Social Icons Block to the home page of your WordPress.com site.
3. Add “Mastodon” as one of your Social Icons (see instructions in step 1).
4. While editing the Social Icons Block, click on the “Mastodon” social icon. An input field will appear below the icon that says “Enter address”. Paste your Mastodon URL into that input field and press the return key. (My Mastodon URL is https://mastodon.social/@vabarger so that’s what I pasted into the field).
5. Now look on the right side of the WordPress edit page. If your “Mastodon” social icon is still selected, you should see “Mastodon” under the “Block” tab (see partial screenshot below). Expand the “Advanced” section and enter “me” in the “LINK REL” field.
6. Click the “Update” button to save your edits on WordPress.com.

Add your WordPress.com website to your Mastodon profile

1. Now log in to your Mastodon instance.
2. Click on “Edit profile” (to the right of your avatar).
3. Scroll down to “Profile metadata”. Enter “Website” as one of your labels and paste your WordPress.com URL for the corresponding “Content”.
4. Click “Save Changes”.

That’s it! Now when people view your Mastodon profile, they should see your website address in green with a green checkmark next to it.

Helpful resource: How to get verified on Mastodon?