McGinty, 19, who will stay at Brunton Park for an initial month, could go straight into the starting line-up for Tuesday night's game at Preston.
Cumbrians manager Greg Abbott told the club's official website: "Manchester United know all about us and know we look after their players when they come up here.
"I've been able to have Sean watched and he has a great physical presence with his size and with the way he plays the game.
"He's very highly thought of down there and hopefully will join us and fit into the squad at a time when we've picked up a few injuries."
Abbott has moved quickly to draft in McGinty, who moved to Old Trafford from Charlton in 2009, as central defenders Peter Murphy (hamstring) and Danny Livesey (hand) are both nursing injury.