This process requires re-formatting of JSON and XML data and is recommended for developers only.
Facebook Comments does not currently offer a feature to export comments all at once, however comments can be programmatically accessed from Facebook one page at a time and then re-formatted for import into Disqus.
Access Facebook Comments
Per Facebook's Can I get comments for a URL via an API? documentation for their Comments plugin:
The comments for every URL can be accessed via the Graph API. Simply make an HTTP GET request to:
https://graph.facebook.com/v2.6/?fields=og_object{comments}
&id=<YOUR_URL>
&access_token=<YOUR_TOKEN>Note that, as this is publicly-visible data, sensitive personal information like email and IP addresses are not included. Hence comments will be imported as guest comments into Disqus and cannot be claimed by registered Disqus accounts.
Re-format for import into Disqus
Using our custom XML import format. This should all end up in one .xml file.
Import into Disqus
At the Disqus admin > Tools > Import > Generic (WXR) page.