The attacking midfielder, who joined the Reds from the Nike Academy in 2013 and has since made 17 league appearances, will spend the rest of the season at Meadow Lane.
Grant, 22, lined up against Notts in this afternoon's Central League Cup match before the deal was agreed.
He said: "We had the game earlier and I did alright. As soon as I heard Notts were interested I came across.
"I would say I'm a high-energy player. I like to get on the ball and make things happen going forward - and I'll work hard off the ball."
Notts boss Kevin Nolan said: "Jorge has brilliant technical ability and will add creativity and flair to our attacking play.
"The move works for both him and us and I'm sure he'll do very well here."
Grant will wear shirt number 17.