Shaw, who missed out on selection for the World Cup despite having been part of the initial training squad, had been training with RaboDirect PRO12 side Scarlets during the summer.
However the 28-year-old, who was at Bristol last season, has now agreed a deal with Leeds.
Shaw said: "I am really pleased to be joining Leeds Carnegie. Having met with Diccon Edwards and seen first-hand the style that Leeds want to play this year, it is exciting to be coming into the squad.
"The Championship is a very tough competition but Leeds have got a squad that is looking to compete at the top of the division.
"I will start training this week but I will have to prove my worth to the squad."
Shaw will compete with Dan White and Craig Hampson for the No.9 jersey, with head coach Edwards pleased with the competition in his squad.
"We are delighted to have signed Robbie," he said.
"He was one of the stand out players for Bristol last year and he will give us strength-in-depth in the scrum-half position."
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.