Originally signed as a rookie in 2015 when playing Gaelic football for Tipperary, O’Riordan made his AFL debut three years later in Round 17, 2018 against North Melbourne. He went on to play 34 senior games of AFL in the red and white and took out the 2021 Best Clubman Award, before being forced into early retirement due to a hip injury.

In 2023 Colin joined the Sydney Swans AFLW program in a coaching position which saw the side make history with a first ever AFLW finals series.

At the conclusion of the 2023 season it was announced he'd step into the role of Academy Head Coach for the U18 Male program, taking over from Mark McVeigh.