The 27-year-old prop will stay at the Twickenham club until at least 2021.
England prop Joe Marler has signed a contract extension with Harlequins, keeping him at the Aviva Premiership club until 2021.
Marler has made 152 appearances for sole club Quins since his 2009 debut, and has won 51 Test caps with England.
The 27-year-old is delighted to commit his future to the Twickenham club.
“Re-signing for my childhood club has made me very happy,” said Marler. “John Kingston has recruited strongly over the summer and he is starting to really mark his identity with this exciting group of players.
“I strongly believe we have a squad capable of going places and I’m really excited for the new season.”
Marler has forced his way into a central role in England’s squad since his 2012 Test debut, and toured New Zealand with the British and Irish Lions in the summer.
“Joe is now established as one of the best loosehead props in world rugby,” said Harlequins rugby director John Kingston. “At 27, excitingly, he is probably only now coming into the peak of his potential.
“He has displayed a real commitment to the Harlequins cause over many years and as an Academy protege, he is another member of the squad who has only ever known one club.
“This news offers a further massive boost to the squad as we prepare for the start of our 17/18 campaign.”