The 23-year-old is a product of the Premiership leaders' academy system, making his first team debut five years ago, and he also featured in Quins' Challenge Cup final-winning side last season.
"I am delighted to have signed a two-year deal with an exciting team who are going in the right direction," Turner-Hall said.
"I have worked very hard over the last two years, and feel I have grown as a player."
Quins rugby director Conor O'Shea added: "Jordan's game has gone from strength to strength.
"He has massive ambitions for himself and his team-mates at Harlequins, and we are looking forward to him pushing on in the coming years and fulfilling his huge potential as a player."
Gilbert has released a new line of rugby cleats. The Gilbert Virtuo 8S is part of the exciting new product. Check it out.
The entire All Blacks apparel line has been updated for 2013/14. Check out the New Zealand All Blacks polo.
The Nike Tiempo is a solid rugby cleat and one of few styles still made from full-grain natural leather.
The Gilbert Blitz 8S rugby cleat is a great cleat at a great price of $69.99. Get a new pair of cleats today.
A cool looking all black rugby cleat with the high performance adidas is known for. Get in the Gear!
Wear the crest of the British and Irish Lions on your t-shirt. A great look for the summer.
$29.99
The All Blacks Performance t-shirt is black with hints of blue from the training jersey. Very Cool.
The New Zealand All Blacks training jersey for 2013/14. Get in the Gear!
The USA Rugby Pro Alternate rugby jersey is perfect for any fan of the Eagles. Get yours to wear during the summer Test matches.
The NEW All Blacks 2013/14 jersey has arrived at World Rugby Shop. Dare to wear the colors of the All Blacks.
