The 18-year-old impressed for the League Two Sulphurites' under-18s sides last term in what was their maiden season competing in the EFL Youth Alliance North East Division.
His form caught the eye of Simon Weaver, and having tracked his progress, Town's manager has now decided to bring Horbury into the first-team fold.
“He’s a strong central midfielder who excelled last year in the under-18s, he was a real driving force for them and got better over the course of the season," Weaver said.
“It’s great having a Harrogate-born lad in there and we can’t wait to see how he develops now as a footballer.
“Paul Stansfield and Josh Law are already working their magic with players, and without our academy we wouldn’t have had that insight into George.
“I remember watching him against Lincoln early on and thought he stood out and he’s got better and better.
“We’re going to involve him in the friendlies and take it from there, but we’ve got high hopes for him.”
Horbury, who has recently completed his A-Levels, hit the ground running last season, scoring Town's academy’s first-ever competitive goal when he netted against Burton Albion at St George's Park.
He describes himself as a "high-energy" midfielder who gives "his all" out on the pitch.
"I’m really grateful for the opportunity I have been given and ready to work hard. It’s a step up in level, but I’ve tried to come in as fit as possible and learn from the pro's in this team," Horbury said.
“Last season was the first season for the academy so there were always going to be some ups and downs, but looking back I thought we did really well and I felt I improved over the year.
“I’m high-energy, get round the pitch and always give it my all, I like to break up the play, break through the lines from midfield and cause problems with my passing and dribbling.
“Everyone is really down to earth and welcoming here and I’m really grateful for Paul Stanfield and Simon Weaver giving me this opportunity.”
Horbury will wear the number 25 shirt for Harrogate.