Ballard spent the formative years of his childhood living in Greece, before his family moved back to England in 2010 and settled in Berkshire.
[4] On 23 August 2022, he made his senior debut and scored his first goal for Southampton's first team in a 3–0 victory against Cambridge United in the EFL Cup.
[5] On 21 May 2023, Ballard made his Premier League debut in a 3–1 defeat to Brighton & Hove Albion, replacing Joe Aribo in the 70th minute.
[15][16] He made his debut for the club on 17 August 2024 in a 3–0 home defeat against Stockport County after he replaced Ashley Fletcher in the 72nd minute.
[18] He suffered a shoulder injury during a 2–0 victory against Huddersfield Town on 24 September 2024, with head coach Steve Bruce later confirming Ballard was expected to be sidelined for several weeks.