The central midfielder will join from Maidstone United, from whom he spent the last 2 years with.
The 24-year-old started his youth career with Charlton Athletic and made one senior appearance for their first-team in the League Cup during the 2015/16 season.
During his time with Charlton, Ollie spent time out on loan with Gillingham, Dagenham & Redbridge and Braintree Town, before permanently signing for Gillingham in February 2017 following his release from the Addicks.
He signed for Maidstone United in September 2017 and made 42 appearances over the last two seasons.
Welcome to Chelmsford, Ollie!