The 19-year-old has signed a four-year contract at London Road, having chosen to join the Posh for an undisclosed fee, following recent interest from Huddersfield Town.
Posh boss Darren Ferguson told the club's official website: "He is a quick left-winger and we have done very well to get him because it looked like he was on his way to Huddersfield Town.
"Crystal Palace were in for him too, so I managed to get him to the club and convinced him that this was the place to be.
"It says a lot for how far we have come as a football club to be beating off competition from two Championship clubs and Huddersfield Town."