The 17-year-old starred for the Championship side in 2016-17 and has now signed his first professional contract ahead of playing for England in the Under-19 European Championship.
Liverpool had also shown an interest in the full-back after he scored seven goals and laid on four assists during his first full season in senior football.
"I’m excited to see what’s in front of me at this club, hopefully we can all push on now," he told FulhamFC TV. "Last year I got a lot of opportunities from the gaffer, and I just want to continue that."
Manager Slavisa Jokanovic also hailed the loyalty the youngster had shown despite the interest from some of the Premier League's biggest clubs.
“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 said.
“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 will be hopeful of helping Fulham improve on an encouraging campaign in 2016-17 during which they finished sixth before losing in the semi-finals of the play-offs to Reading.