The 21-year-old former Chelsea trainee has established himself as a key player in Oscar Garcia's first-team squad this season.
Seagulls boss Garcia told the club website: "I am delighted for Rohan. He has earned this contract with the way he has trained and played ever since I came to the club.
"He has an excellent attitude every day, he looks after himself and works hard in training; and we are all seeing the benefit of that with his performances on the pitch.
"It is nice for the club to reward that hard work and professionalism with this new contract and I am very pleased for him."