The club offered Chappell a contract extension but the all-rounder has instead decided to sign a three-year contract at Trent Bridge.
Chappell has taken 31 first-class wickets in 14 appearances at 33.09 apiece including a career-best six for 44 against Northamptonshire CCC this season. He has also scored 532 runs at an average of 31.29 with a best of 96 on debut against Derbyshire CCC in 2015.
The 22-year-old, who came through the Academy system at Leicestershire CCC, claimed 22 wickets in white ball cricket for the Foxes, as well as contributing 189 runs.
He said: “I have really enjoyed my time at Leicestershire County Cricket Club and I would like to thank everybody at the club for making it so enjoyable. I’ve loved every minute of it.
“Working with Nico [Paul Nixon], Mase [Matt Mason], and all of the coaches has been absolutely brilliant, and the team has made good progress in 2018. We’ve had some enjoyable wins in the [Specsavers County] Championship.
“But the opportunity to test myself playing Division One cricket with Nottinghamshire is an opportunity that I couldn’t turn down. I want to play for England in the future, and I think the best chance to do that is by playing in Division One.”
Leicestershire CCC Head Coach Paul Nixon said: “We are really disappointed to lose Zak [Chappell], as he was an important player across all formats for us. He has bowled some excellent spells of fast bowling and made some useful scores with the bat.
“We really wanted him to continue his development with us, and we made him a very good offer to keep him with us. Sadly, Zak has opted to sign for Nottinghamshire to play Division One cricket, and the club wishes him well in the future.”
©Cricket World 2018