This comes as great news for Quins RL ahead of their first home game of the season at the Twickenham Stoop this Saturday.
In autumn Purdham led England to victory in the Federation Shield and was named player of the series.
He joined the London club in 2002 from Whitehaven Warriors and last week played his 101st game for the club. In 2006 Rob set a new club record of points scored in match (34) and goals in a match (13) in last year' Challenge Cup win against Barrow.
Rob commented: "Playing for England was a great experience and it has given me a huge lift as a player. Every kid dreams of captaining his country. Hopefully that experience will give me a big boost for this season and help Harlequins as well."
I'm really pleased to extend my deal with the club and I think we have all the right ingredients to achieve the success we are striving for."
Last week's win was no surprise to us at all. We have worked really hard as a squad in the pre-season and with the hard work will come rewards."
Brian McDermott knows he has a very good leader in his camp but is quick to point out Purdham's many other talents: "Rob has proven he is a fine leader and he is relishing his role as captain at Quins."
He is also a very, very talented player who will play a major role in all that we do as a team this season. His skills are top-shelf, he will always get his job done, and he has that game-breaking ability that every successful team needs."
Harlequins RL are expecting to make another major announcement in the next couple of days.
Andy Smith, who joined the club this week from Bradford, has been included in Saturday's 20-man squad and allocated squad number 24.
Adult Season Tickets can still be purchased from just £99 with a child's Season Ticket included FREE of charge with every purchase. Adult tickets start at just £12 and a Family Ticket (2+2) costs just £40. Call 020 8410 6000.
20-man squad as follows:
Gafa, Grayshon, Heckenberg, Hill, Hopkins, McCarthy-Scarsbrook, McLinden, Melling, Mills, Orr, Paul, Purdham, Randall, Rinaldi, T Smith, A Smith, Sykes, Temata, Wells, Worrincy
Harlequins v Salford City Reds, 6pm Saturday 17th February, Twickenham Stoop