The 29-year-old has played his entire professional career with Quins, making more than 200 appearances and captaining the side between 2010-2014.
He was part of the team that won the 2012 Aviva Premiership title as the Twickenham Stoop outfit beat Leicester Tigers in the final.
Robshaw has also skippered England on 42 occasions, but his position as captain and also in the side is now under threat after the Red Rose's woeful displays in failing to make the quarter-finals of the recent World Cup.
Coach Stuart Lancaster has paid the price with his job and it remains to be seen whether the new man wants the Surrey-born back-row star as his leader.
But Robshaw has no negative thoughts and is relishing the chance to bring further success to west London.
"I'm looking forward to seeing what the future holds for the club and I'm extremely excited to keep pushing for silverware with both Harlequins and England," he said.
"I would like to thank all of the supporters for their continued support and look forward to being with this great club in the years to come."