The 23-year-old wing, who has won seven international caps, has scored nine tries in 30 outings for Quins since joining from London Irish in 2014.
"Marland is a young man with boundless potential and we will work with him to make sure he fulfils it," director of rugby Conor O'Shea said.
"We know within this group he will go from strength to strength."
Harlequins have not disclosed the length of Yarde's new deal.
St Lucia-born Yarde said it was "an easy decision" to extend his contract with the 2012 Premiership champions.
"Since joining, I've enjoyed being part of a great team with some exceptional players," he added. "We have a side that is truly capable of beating anyone and I'm excited to be a part of that."
Yarde made his England debut against Argentina in 2013 but he was not included in the 31-man squad for the World Cup earlier this year.
England international Marland Yarde has signed a new contract with Premiership club Harlequins.