As described in historical dictionaries

Sorry, we don't have any historical texts which describe the Eynon surname. That's probably because it was very rare in Great Britain more than a century ago.

Surname type: From given name or forename

Origin: Celtic

Region of origin: British Isles

Country of origin: Wales

Religion of origin: Christian

Language of origin: Welsh

BritishSurnames.uk is a Good Stuff website.