Yes. Publons accepts manuscript reviews submitted to journals and conferences.
You are able to add your conference reviews as you would a journal review. Please enter the details of your review on our pre-publication form and where it asks for the 'Journal Title' simply type in the name of the conference instead (note: as with journals, if a conference is not already in our database you will need to contact us to have it added).
Conference reviews can be verified in the same way as reviews of journal articles by simply forwarding your receipts to firstname.lastname@example.org.
If you no longer have those receipts but have access to the review submission system you can take screenshots and send them to email@example.com (with the Journal name, date of review and your name/login clearly visible).