The 17-year-old is expected to have a bright future at Craven Cottage but he has yet to be given too many opportunities by Jokanovic.
He signed his first deal on his 17th birthday, with the Cottagers tying him down until the summer of 2020.
O'Riley made his debut in the 2-0 win over Wycombe in the Carabao Cup in August and his performances in training and reserve games has caught the eye of Jokanovic.
He told Get West London: "[The contract] It's good, it's another 17-year-old player and in the last few months he is working with us.
"Technically he has impressed us in all the days and he's still young and working well, he's pushing himself to be strong and is fighting to be part of the competition team.
"Why not? It's another young man with great mentality who wants to learn things and soon we will know how much time he will need to be part of the Fulham competition squad."