Watford defender Reece Brown played 90 minutes for Barnsley against Hull City on Saturday after joining the Tykes on trial last week.
The 22-year-old centre-back started and played the full game as the League One side drew 1-1 with the Tigers at Oakwell.
Brown signed for Watford on a two-year deal following his release by Manchester United last summer and made just three appearances, with only one coming in the league.
The former England Under-19 and Under-20 cap ended the season out on loan at League One side Carlisle United but could not prevent the Cumbrians' slide into League Two.
Brother of Sunderland’s Wes, Brown had been involved in Watford’s pre-season preparations, making three appearances, the last of which came at Wealdstone last Wednesday in and Under-21s friendly.
Barnsley fell behind to a Shane Long strike but equalised through summer signing Connor Hourihane in the second-half.