The former Newcastle academy graduate made the switch to the Cherry and Whites from Tynedale in 2009 - with the 25-year-old going on to make 45 appearances.
And Harden's form this season saw him called up to the England Saxons set-up - as well as earning the attentions of a number of other clubs.
However Harden, who was born in Australia before moving to England as a youngster, had no hesitation in signing a new deal.
Harden said: "I've got all my mates here, and I'm very happy. There's an element of loyalty in this, definitely.
"You can't ask for a better place to perform than Kingsholm, and the fans are great.
"You can't deny there's always an aspect of having to earn a living, but when the professional situation is right, and that comes on top of that fantastic support, then you can't be in a better scenario."
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.
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.