The 2018 Cardiff National Eisteddfod was held in Cardiff Bay, Wales, from 3 to 11 August 2018. It was the seventh time the National Eisteddfod of Wales had been held in Cardiff. The 2018 event was billed as the Eisteddfod with "No fences" because it dispensed with the traditional enclosed 'Maes', or entrance fees to the event location. It made a £290,000 loss, but its popularity led to the suggestion of future Eisteddfods without fences.

The National Eisteddfod of Wales is the largest of several eisteddfodau that are held annually, mostly in Wales. Its eight days of competitions and performances are considered the largest music and poetry festival in Europe. Competitors typically number 6,000 or more, and overall attendance generally exceeds 100,000 visitors, the highest recently being 118,000 attending the 2022 festival. The 2018 Eisteddfod was held in Cardiff Bay with a fence-free 'Maes'. In 2020, the event was held virtually under the name AmGen; events were held over a one-week period.