He previously played for Montrose over two spells either side of a season with St Patrick's Athletic in the League of Ireland Premier Division.
Having impressed at Junior level for Lochgelly Albert where he had scored 17 goals in half a season, Rennie was signed by Scottish League Two leaders Montrose on an 18-month contract on 19 January 2018.
[7] The 2019–20 season proved to be a quieter one for Rennie as by January he had made just 11 appearances and scoring 2 goals amidst transfer interest from other clubs.
[15] He made his competitive debut on 14 February 2020, playing the full 90 minutes as his side lost 1–0 against Waterford in the opening game of the season at Richmond Park.
Rennie, in search of game time was sent out on loan to Berwick Rangers but was quickly recalled during parent club's Montrose injury crisis.