The 19-year-old returned to the Britannia Stadium this month following a six-month loan spell at Leyton Orient where he scored three goals in 22 appearances.
Birmingham-born Brunt, who has also had loan spells at Tranmere and Luton, came through the youth ranks at rivals Bristol City before moving to Stoke in 2010.
Manager John Ward said: "He is a big lad and a line leader. He is what you would describe as an old fashioned centre forward, and he has goals in him, which is obviously important.
"I have said before that I have strikers here who need some help over the next 19 games, and I think Ryan's presence can provide what we are looking for and take some of the pressure off."