The 22-year-old attacking midfielder, who is originally from Eastbourne, joins from National League side Torquay United.
Fenwick’s career started at Lewes before he was signed at the age of 18 by Crystal Palace where he played ten games for the club’s under-21s.
After just over a year in south London, he left and spent time at a number of other clubs, including Cardiff City.
He joined Torquay in July 2015 and made seven appearances before being released just before Christmas.
Fenwick trained with Truro last week and impressed manager Steve Tully, who said: “He’s a front man who can play in many positions. He could play off Isaac Vassell or Matt Wright up top. He could play behind the strikers or he could play on either wing as he’s two-footed. He’s very technical, has an eye for goal and isn’t afraid to shoot on sight. He will be a very good addition to the squad and we’re delighted to have him.”
Fenwick will be in the squad for Saturday’s FA Trophy match at Treyew Road.
Meamwhile, striker Matt Wright will be out for two to three weeks with a chipped bone in his foot.
Colin Bradbury