Sussex-based Harris joins Boro having been with Bostik League South outfit East Grinstead Town since November 2016.
The 21-year-old, who is from East Grinstead and lives in the town, signed for the Wasps after he was released by SkyBet Championship side Barnsley.
He joined the Tykes in February after three years at Brighton & Hove Albion, during which time he made four appearances and scored one goal at National League side Aldershot on loan.