King has been at the club since Under-12 level, progressing steadily through the Academy ranks while consistently playing above his age group. He first emerged as part of the Under-15 side that reached the U15 National Floodlit Cup final in 2021/22, before earning his scholarship ahead of the 2023/24 season.
He made an immediate impact at Under-18 level, scoring on his league debut against Liverpool in September 2023 and following it up with another goal in a 3-3 draw against Brighton later that month.
His attacking influence from defence continued throughout the season, including a dramatic 94th-minute winner against Fulham that sent Palace into the U18 Premier League Cup quarter-finals, as well as a brace – featuring an 80th-minute header – in a 2-1 FA Youth Cup win over Plymouth Argyle.
By the end of 2023/24, King had made 31 appearances in all competitions, scoring six goals and registering two assists, while also beginning to demonstrate his versatility with spells in midfield.
He continued that development in 2024/25, captaining the Under-18s on occasion and making 27 appearances across the season, contributing two goals and one assist. His progress was rewarded with a first taste of Under-21 football in February 2025, debuting in a 2-0 win away at West Bromwich Albion before going on to make eight appearances at that level.
The 2025/26 season marked a significant step forward following a strong return from injury, as he established himself as an important figure in Darren Powell’s Under-21 side. He made 23 appearances in all competitions, missing only one match he was available for, underlining his consistency and reliability.
A defender who contributes at both ends of the pitch, King scored three goals during the campaign – including decisive strikes in Premier League 2 wins over Aston Villa and Blackburn Rovers – while also providing four assists.
His creative influence included intelligent flick-ons and lofted passes leading directly to goals against Nordsjaelland and Liverpool in the Premier League International Cup.
Defensively, he was equally influential, producing key interventions in important moments, including goal-line clearances against Juventus and Borussia Mönchengladbach in Europe, as well as a vital extra-time block in the PL2 play-off victory over Liverpool.
His performances were rewarded with a senior debut in the UEFA Conference League against KuPS Kuopio, where he started and played 76 minutes in a composed display that drew praise from Oliver Glasner for his maturity and consistency.
King’s progress was further recognised through inclusion in first-team squads against Aston Villa and Macclesfield, alongside his first Republic of Ireland Under-19 call-up and debut, marking another important step in his international development.