Glaswegian winger Galloway joined Leeds in August 2019 from Carlisle United as part of the same summer in which United also signed Liam McCarron from the Cumbrians.
The 20-year-old had a spell on trial at Barrow last November but the League Two outfit opted against pursuing a longer deal for the Whites youngster.
But Galloway joined Northern Premier League outfit FC United on Tuesday and then made his debut in the same night's seven-goal thriller at home to Whitby Town.
The midfielder's arrival at the club was announced during the half-time interval, at which point he was introduced from the bench as part of a contest in which FC United fell to a 4-3 defeat.
Galloway last featured for United's under-23s in November 2020 and his contract at Leeds expires next summer.
The youngster's loan move to FC United is until the end of the season.
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