Betty, 24, will link up with the Warriors ahead of their pre-season training camp in Geneva and forthcoming friendlies against the Melbourne Rebels and Argentina.
The Bristol-born forward becomes Worcester's 13th new signing ahead of their return to top-flight English rugby.
Betty's arrival at Sixways, though, comes with former Worcester and England captain Pat Sanderson battling to make September's Premiership kick-off.
Flanker Sanderson has been sidelined since suffering a shoulder injury during Worcester's Championship play-off clash against Bristol in March.
"Pat has taken longer than he, and we, would have liked to repair, and he remains in rehabilitation with us," said Worcester head coach Richard Hill.
"At the moment he is unlikely to make any of the pre-season games, and therefore there is a danger that he will not be match fit for the start of the season."
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.