The winger made his U21 breakthrough last season.
Kamara, 18, told the club's website: “I feel really delighted to have my family watch me sign my first professional contract. It’s been a lot of hard work throughout the years, but I’m happy that they can see that it’s paid off.
“It gives you that sense that, if you do work hard, things will be given to you. I’m going to keep doing the same in the future.
“It was an easy decision. The coaches and staff around here are very welcoming and bring out the best in me, so I’ll keep improving as a player and a person.
“Next season, I’m going to try to build on my goalscoring. I know it’s going to be harder for the under-21s, but I have to level up and keep improving.
“I’ve been going through this journey with my teammates for a long time now, from a young age, maybe under-10s, so it’s nice to see all of us reaping the benefits of our hard work and being together.”