The 19-year old right-back joins the Fury from North Queensland State League club Razorbacks for the remainder of the current season.
Fury football operations manager Robbie Middleby said that Sipi was a player who had been on the club's radar for a while.
"Lorenzo is someone Ive been following closely for over 12 months and we believe he has the potential to achieve great things with the Fury,'' he told the Townsville Bulletin.
''He has been training full-time with the squad for the past month and has really impressed both Franz (Straka, head coach) and Stuart (McLaren, assistant coach) with his attitude and aptitude.
''Lorenzo is a strong player, who is fast and confident with the ball at his feet plus his versatility means he provides the coaches with further options this season.''