The junior walk-on has two years of eligibility remaining and can play for Cal Poly immediately.
"Paulo has great range on his jumper and we like his size and strength for a wing," Cal Poly head coach Joe Callero said in a statement. "He could compete for playing time at the two or three spot his first year with us. We love the depth and experience he'll bring to our team."
Cruz played 21 minutes in eight games as a sophomore this past season, including a nine-minute stint against Sacred Heart on Nov. 18 in which he grabbed a career-high two rebounds.
The San Diego native appeared in six games as a freshman in 2015-16.
Matthew Weyand, a guard from Mater Dei High School, will replace Cruz, per Scout.com’s Jason Scheer.
Follow Ryan Kelapire on Twitter at @RKelapire