The 18-year-old defender made seven appearances for the Reds last season.
"He deserves it because he did so well for us towards the end of last seaaon," said Director of Football Damien Comolli.
"Flano had a long time left on his current deal but we thought it was the right thing to do to reward him for what he's done. His attitude is absolutely terrific and as you see him on the pitch committed, dedicated.
"It's what he's like off the pitch aswell. He's very professional. He knows how to look after himself, he knows who to listen to and that's why he has improved so quickly."