The former Brumbies half-back was brought in on a short-term deal in September with Junior Poluleuligaga away at the World Cup with Samoa.
But the Australia A cap has impressed head coach Rob Baxter, and will now remain at Sandy Park for the rest of the campaign.
"Pat's deserved it, he's earned it the hard way," said Baxter.
"Initially we weren't selecting him for the Premiership games because both Haydn (Thomas) and Kevin (Barrett) were bang on form and playing well, so it was difficult for him.
"However, a few A games and the LV= Cup games come along and things changed for him. He played well; he led the team well and all of a sudden you start to see a lot of good things, which I suppose has influenced quite a bit."
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.