The teenager started 17 Championship games, came off the bench in a further nine, and also contributed with seven goals and three assists in all competitions.
A number of top-flight clubs were reportedly sniffing around, but the England Under-19 international has opted to put pen to paper on a deal that ties him down to Fulham until 2020.
"I'm excited to see what's in front of me at this club, hopefully we can all push on now," Sessegnon told the club's official website. "Last year I got a lot of opportunities from the gaffer, and I just want to continue that."
Manager Slavisa Jokanovic added: "Ryan joined our first-team squad early during pre-season last summer. One year on, I'm pleased that Ryan's performances have been rewarded with his first professional contract with Fulham and he will continue to be part of our project in the future.
"He is an exceptional young player who has demonstrated loyalty and commitment by continuing to serve this club since his progression from the academy."
Sessegnon joined the Cottagers' youth system in 2008.