Follow these steps to block a bidder on eBay:

Blocking specific bidders or buyers on eBay prevents them from bidding on your current or future listings, purchasing your items, or contacting you via eBay’s messaging system. This is useful if a buyer has been disruptive, failed to pay, or you simply don’t want to do business with them again.

Blocking bidders helps maintain a smooth selling experience by preventing problematic users from interfering with your auctions or fixed-price listings.

Here’s a clear, step-by-step write-up you can use or adapt:

Go to eBay.com and sign in to the account associated with your seller profile.