The 39-year-old is looking to further his career away from the playing side of the game, although he will be available to play should his services be required.
"We're pleased to have agreed a deal with Gary who has a wealth of experience and is uniquely qualified to serve us at this stage of his career," said Nottinghamshire's director of cricket Mick Newell.
"He was keen to take the next step towards a full-time career in physiotherapy but still feels that he can contribute to our coaching team and provide an option for those games away from Trent Bridge where we may opt to play two spinners."
Keedy played a key role in Lancashire's LV= County Championship triumph in 2011, finishing as leading wicket-taker with 61 scalps.
Following Lancashire's relegation the following season, Keedy moved to Surrey, although he only played six championship matches this year as they too were demoted from Division One.