He made his League debut for Ross County against Greenock Morton in the Scottish Championship, coming on as a substitute.
[4][5] In June 2021, Gallagher joined Scottish League Two side Forfar Athletic on a season-long loan.
[6] On 29 January 2022, Gallagher joined NIFL Premiership side Cliftonville on loan for the remainder of the 2021–22 season.
[7] After being released by Aberdeen in June 2022, Gallagher joined Highland League side Formartine United.
[8] On 30 July 2024, Gallagher returned to Elgin City on a two-year deal, after playing for the club on loan earlier in the year.