A native of Avoca, County Wicklow,[1] Bolger came through St Joseph's Boys, before moving to the academy of League of Ireland club Shamrock Rovers in 2016.
While at St Joseph's Boys, he was part of a formidable side that included fellow future professional footballers Joe Redmond, Brandon Kavanagh, Jonathan Afolabi, Andy Lyons, Promise Omochere, Ryan Burke and Max Murphy among others.
[2][3] Bolger made his senior debut for Shamrock Rovers on 9 September 2016, when he replaced Stephen McPhail from the bench in a 5–0 defeat to Cork City an FAI Cup tie at Tallaght Stadium.
[6] He made his first appearance in European football on 6 July 2017, when he came off the bench in a 1–0 win at home to Stjarnan of Iceland in a UEFA Europa League tie.
[7] On 16 September 2017, he started in the 2017 League of Ireland Cup Final, but was sent off in the 64th minute for a second yellow as his challenge was late and high on Dundalk defender Niclas Vemmelund as his side lost 3–0.
[15] He made the first team squad just once, remaining an unused substitute, while all 11 of his appearances were with the club's reserve side Shamrock Rovers II in the League of Ireland First Division.
[16] On 30 January 2021, Bolger was loaned to newly promoted League of Ireland Premier Division side Longford Town until the end of June 2021, when his contract at Cardiff City expired.
[29] On 25 July 2024, he featured in his side's 3–1 win over Vaduz of Liechtenstein in the UEFA Conference League, replacing Romal Palmer from the bench in the 76th minute.
"[35] Former teammate Ronan Finn speaking about Bolger when he was 17 years old, said "Paul Scholes was a small midfielder and Aaron has a low centre of gravity.