Youth career Raised in Ellistown, a townland near
Rathangan,
County Kildare, Noonan attended Ardscoil Rath Íongahain and began playing his schoolboy football with Monasterevin. He later played for
Crumlin United, then
Celbridge-based club Ballyoulster United, before signing for the Academy of
League of Ireland club
St Patrick's Athletic in 2022. He initially played for the club's under-15 side, before progressing through the under-17, under-19 and under-20 sides over the following 3 seasons.
St Patrick's Athletic On 3 February 2024, Noonan made his senior debut for
St Patrick's Athletic, replacing
Ruairí Keating from the bench in the 76th minute of a 3–1 win away to
UCD in the
Leinster Senior Cup. On 17 September 2024, he scored his first goals in senior football, scoring twice in a 3–1 win over
Maynooth University Town in the Semi Final of the same competition. On 8 October 2024, he opened the scoring in the Final of the
2023–24 Leinster Senior Cup in an eventual 2–1 win over
St Mochta's at
Richmond Park. His performances in the
Leinster Senior Cup led to manager
Stephen Kenny giving him his league debut on 14 October 2024, replacing
Aidan Keena in the 89th minute of a 3–1 win over
Bohemians at
Dalymount Park. Later that month he was linked with a move to
Premier League champions
Manchester City.
Shamrock Rovers On 15 January 2025, he signed for fellow
League of Ireland Premier Division club
Shamrock Rovers, turning down
St Patrick's Athletic's matching contract offer as they had
Mason Melia and
Aidan Keena ahead of him in the pecking order, as well as Noonan being raised as a Shamrock Rovers fan by his family. Noonan became the youngest ever scorer in
UEFA Conference League history when he scored for Shamrock Rovers away at Norwegian side
Molde in his debut for the club on 13 February 2025. He scored the first senior league goal of his career in his 11th senior league appearance on 21 April 2025, giving his side a two goal lead in an eventual 3–2 loss at home to
Bohemians in the
Dublin derby at
Tallaght Stadium. In January 2026, his club turned down two bids from
Bundesliga club
Hoffenheim of around €1 million, as the bids fell below Rovers' €2 million valuation of Noonan. A fee of €1.8 million was then agreed between the clubs before the move fell through as Noonan did not want to move to Germany, with his mother then lodging a complaint to the
Football Association in London about an alleged arrangement between Shamrock Rovers and another party, resulting in the
FA notifying the issue with the
FAI and
FIFA who began an investigation into the club and the player's agent regarding a third-party cut of the potential transfer fee. ==International career==