Irish teenager Curtis joined the Blades on a long-term deal until the summer of 2027 following the expiry of his association with St Partick's Athletic in the League of Ireland. Born in Navan, Curtis made his Premier League debut for United as a substitute against Everton at Goodison Park in May 2024.

Having made his St Pats debut at the age of 15 years and 255 days old, the Republic of Ireland youth international won the PFAI Young Player of the Year award in 2023.