The 23-year-old served as a backup to Steve Gregory in the 2013 season seeing limited playing time, but following Gregory's and fellow defensive back Adrian Wilson's release, Harmon is expected to start for the club next season.
"Steve Gregory was like a big brother/uncle to me, somebody that literally sat me down all the time and watched film with me, broke things down, so he's definitely going to be missed," Harmon told ESPN.
"It's an opportunity for me to show that I am capable of playing and starting. But it all counts towards me. I have to show my worth to Coach Belichick and the coaching staff, and I'm eager to do that."
Harmon was drafted 90th overall by the Patriots in 2013.