The 28-year-old has moved to the League One outfit after Adam Dugdale's emergency loan switch from Crewe Alexandra finished on Monday.
"We are low on numbers in defence, so I'm delighted to have signed Jim for a month," Rovers manager Ronnie Moore told the club's official website.
"We've got a lot of young players on the pitch at the moment so Jim's experience will be useful. He's a player I've been keen on for a while. He can play in a couple of positions, is big and strong and uses the ball well."
McNulty has made one appearance for Barnsley this season.