[1] Following the withdrawal of English clubs from, and the subsequent demise of, the British and Irish Cup in 2018, the Irish Rugby Football Union and the Welsh Rugby Union agreed to create a new development competition, the Celtic Cup, for the emerging professional players from the four Irish provinces and four Welsh regions in 2018.

The name had been used previously between 2003 and 2005 for a short lived single elimination knockout competition between teams in the then Celtic League.

The new tournament, which features development squads from Pro14 teams Connacht, Leinster, Munster, Ulster, Cardiff Blues, the Dragons, the Ospreys and the Scarlets, aims to provide a learning environment for players, coaches and referees by recreating the week-to-week challenges presented by senior professional rugby.

The eight teams were divided into two conferences of four Welsh regions and four Irish provinces.

Leinster A retained their title, defeating fellow Irish province Ulster A 31–10 in the final at Energia Park.