The 21-year-old forward has signed a one-year contract after five goals in three Rovers matches.
He was released by Manchester United in the summer of 2020, having been with the club since he was six. He has played for England at under-17 and 18 level but his only senior football came on loan in Norway with Tromso in 2019, scoring twice in seven games.
After leaving Old Trafford Barlow had trials at Championship side Stoke City, League One Ipswich Town and League Two Salford City but it is at the Keepmoat where he has made the biggest impression, playing on either side of new manager Richie Wellens front three.
Wellens also came through the Red Devils academy without playing for the first team, making his senior debut at Blackpool and later going on to have two spells in Doncaster's midfield.
Summer signings Tommy Rowe and Ro-Shaun Williams also came through the Manchester United finishing school before breaking into senior football lower down the pyramid, whilst Kyle Knoyle has a Premier League upbringing with West Ham United, and Jordy Hiwula failed to make the grade at Manchester City.
Wellens has also signed Ben Close and loanees Matt Smith and Tiago Cukur in his first window as Rovers manager. He retains an interest in fellow trialise Louis Reed and are looking to loan a goalkeeper to provide competition to Louis Jones, but budget restrictions may mean Wellens have move players on first.
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