Gabriel, who was at Southend as a youngster, has featured regularly for the Forest Under 23s in 2019-20 and also came on as a second-half substitute for ex-Iron loanee Joe Lolley in the Carabao Cup third round tie against Arsenal at the Emirates Stadium.
The defender was offered a professional contract at the City Ground in January 2016 with academy manager Gary Brazil citing him as 'an exceptional talent'.
A strong tackler, who is fast, tricky and capable of beating his man, the 21-year-old will hope to make his debut in Saturday’s home encounter against Crewe Alexandra.
He will wear the No 15 shirt.
