The 19-year-old, who can play out wide or behind the main striker, played five games in a previous spell at The Valley last season.
"He is such a talented player and we only got to see a glimpse of what he could do last time he was here," Addicks boss Karl Robinson said.
“I've watched him a lot since he's come back from injury and he is a phenomenal talent. I don't think it is any secret that we wanted to bring him in over the summer
“The fans will have seen how quick, powerful and skilful he is from his first spell with us. He is a Championship quality player already and he comes to Charlton now with a point to prove."
Charlton next play Oldham in a home League One game on Saturday.
They are ninth in the table, four points outside the play-off places.