The 23-year-old parted company with the U's on Tuesday after having his contract cancelled by mutual consent.
Pentney joined the club in August 2010 but failed to make a senior appearance during his two-and-a-half-year spell at the Weston Homes Community Stadium.
He did however make a number of loan moves including spells with non-league clubs Woking and Chelmsford City.
"It's disappointing to leave Colchester but I've come to a point in my career where I need to play games," Pentney told The Daily Gazette.
He added: "I always hoped that I would get a chance at Colchester but things didn't work out."