Last season, the Brazilian netted five goals in 30 appearances in the Championship as Fulham missed out on promotion to the Premier League through the playoffs.
However, the Blues have revealed that the 23-year-old will spend another year at their West London neighbours as he continues to gain experience in English football.
Meanwhile, Piazon has agreed a two-year extension to his contract at Stamford Bridge.
The forward has spent the last five years on various loan spells away from the club but he has been given a glimmer of hope for the future by being allowed to pen terms until 2020.
Piazon's last outing for Chelsea came in December 2012 when he was introduced as a 74th-minute substitute during the 8-0 thrashing of Aston Villa.