The 21-year-old defender has been with Chesham for three years, after spells with West Ham and Barnet. Iain Dowie's (Oldham assistant manager) brother recommended Hall to the club and he has joined after a he impressed during a trial period.
The youngster has signed a two-and-half year contract at Boundary Park.
Meanwhile, Oldham have completed the signing of Andy Goram on a short-term contract.
The former Scottish international will provide cover after number one Gary Kelly was injured.
