Born in Bristol, Mullins attended St Mary Redcliffe and Temple School and graduated from SGS Filton.
[5] Mullins was part of the Irish U20 side that won a grand slam at the 2022 Six Nations Under 20s Championship.
[8] He was part of the Irish team that won the Rugby Europe Sevens Championship Series trophy in July 2023, scoring a last minute try against Great Britain in their final match in Hamburg to ensure Ireland finished top of the standings.
[10] Mullins scored 2 tries in Pool game against Japan and Quarter-Final match against Fiji.
Mullins is eligible to play for Ireland through his grandmother who was from Cavan and his grandfather Richard, who was from County Meath.