[8][9] Shortly after winning the Elite Youth League, Reilly signed his first professional contract with Hamilton Academical at the age of 16, penning a two-year deal.

On 1 October 2020, following a successful trial period, Reilly signed a one-year deal with Scottish League One club Partick Thistle.

[15] Reilly would have a stand-out 2022–23 season, scoring 24 goals and providing 19 assists over 39 games for Albion Rovers, and was awarded League Two's player of the month both in November 2022[16] and in January 2023.

[17] Despite immense speculation over his future in January[18] including having supposedly signed a pre-contract agreement with Dundee,[19] Reilly remained with Rovers, with manager Brian Reid saying it would take "something exceptional" to encourage the relegation-threatened side to sell.

[25] On 23 February 2024, After impressing in short stints for Dundee and fighting intermittent injury issues, Reilly joined Scottish Championship club Arbroath on loan until the end of the season to get regular playing time.

[28] On 1 October, after recovering from injuries through the summer and early in the season, Reilly joined Scottish League One club Inverness Caledonian Thistle on loan until January 2025.