The 21-year-old has put pen-to-paper to rival Peter Crook for the goalkeeping jersey at the Jakemans Community Stadium.
Reflecting on the decision to sign former Bradford City and Derby County youngster Sykes-Kenworthy, United manager Craig Elliott said: "We need competition throughout the squad and it was important to get two keepers in.
"He's a good young lad with real potential and the opportunity is there for him to go on and impress."
Sykes-Kenworthy will wear squad number 13 for the Pilgrims.