The 18-year-old is in his first year at Loughborough University and will join the Sussex squad at the completion of the academic year early next summer.
A left-handed batter and left-arm wrist spinner, the East Grinstead player made his first team debut in the penultimate match of the 2021 Championship season against Leicestershire.
Part of the Sussex pathway since he was an under-11, the former Lindfield young gun captained his county age group from under-16 level onwards.
He also captained the London & East side to the semi-finals of the ECB Super 4s competition for under-18s last summer, as well as making his county 2nd XI debut.
Born in Frimley, Surrey, Hinley was a pupil at Warden Park Academy in Cuckfield before attending Eastbourne College for sixth form.
He said: "I'm delighted to have signed a deal with the club I've been with since I was ten. I'm grateful for the opportunity to learn, improve and hopefully contribute towards winning games for Sussex."
Sussex’s Championship & One-Day head coach, Ian Salisbury said: "Tom’s been someone we’ve paid very close attention to during his time on the Academy. As a top-order batter, a very promising left-arm wrist spinner and a gun fielder, he has huge talent across the disciplines.
"We got a chance to look at Tom around the professional set-up at the end of the summer and liked what we saw. We think he’s got a bright future at Sussex and this contract will allow him to complete his studies while making sure he continues to develop as a cricketer."
The club’s T20 head coach, James Kirtley added: "Tom had a really good season last year and impressed at the Super 4s. It would have been easy to overlook his performances with many of his contemporaries playing first team cricket, which indeed Tom did at Leicester, but he is an exciting striker of a cricket ball and there are very few left arm wrist spinners around, which gives him a unique edge.
"He quietly goes about his business, and I look forward to seeing his development."