The 27-year-old started his career with Llanelli Scarlets before joining Brive on a two-year deal in June 2008.
He has had spells with the Ospreys, London Welsh, Scarlets and the Dragons since returning to the UK.
Blues director of rugby Phil Davies told the club's official website: "Liam is a player that I am familiar with having coached him as a 19-year-old with the Scarlets.
"He is a very talented scrum half who has a great pass, a good kick and does the basics well.
"He played alongside Andy Goode in Brive and has come home looking for an opportunity to play.
"He will give us extra cover at scrum half for the rest of the season with Rob Lewis having returned to London Welsh on a loan spell."
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.