The 20-year-old Stuart Smith has been behind England's Andy Gomarsall in the Kingsholm pecking order, and has signed a one-year deal at Headingley, following their decision to release Irishman Derek Hegarty.
Leeds' director of rugby Phil Davies said of the move: "Clive is an extremely talented young player who has all the ability to develop into an international class scrum-half.
"He has shown at Gloucester this season that he can handle playing in the Zurich Premiership and hopefully he will develop even further at Leeds.
"Derek [Hegarty] has always given 100 per cent during his time at Leeds and has been a tremendous person to have involved with the squad, both on and off the field.
"He stated that he would like to return home to Ireland to continue his playing and I was glad that we could come to an agreement."
On the decision to release wing Chris Hall, Davies added: "Chris has spent three seasons with us and I would like to thank him for his efforts whilst at the Tykes and wish him all the best for the future."
Leeds enter their first season in the Heineken Cup when the new season gets underway, with their off-season spending seeing the arrival of stars such as England wing Phil Christophers, Italy openside Aaron Persico and Scotland fly-half Duncan Hodge.
By Mark Smith