The 17-year-old has already scored 11 goals and four assists this season, with January proving an especially fruitful month with six strikes from four games.
Sessegnon, who was also named PFA Player of the Month for January, was instrumental in Fulham winning all four of their games to climb into the playoffs.
"Ryan has shown his talent and desire and deserves the award for January. He is a young player with a very big future and is an important member of our team," Fulham manager Slavisa Jokanovic told the EFL website.
"Winning this award provides recognition for the good work he and the team have done so far and I expect he will continue to show his skill and qualities to help us for the rest of the season."
Sessegnon added: "It's a great feeling to be named the Championship Player of the Month but I think it's credit to the team and the way we've all been playing in January, which has allowed me to get this award. It's an amazing feeling.
"It's been down to the gaffer playing me in a higher position allowing me to play further forward and scoring more and creating more goals. At this minute, I'm liking my role further up the pitch with the ability to contribute goals and assists."